The First 90 Days as Head of Growth at a Startup (and How Founders Should Judge You)

I've walked into four different startups as the "growth person" over the past decade. Each time, the same pattern plays out: there's a flurry of introductions, a firehose of context dumps, vague expectations about "unlocking growth," and an unspoken clock ticking in the background. Everyone is watching to see if you're the real deal or another marketing hire who'll spend six months optimising Facebook ads, produce some dashboards nobody looks at, and quietly leave when things don't "scale."

The first 90 days determine whether the next 900 will matter.

The uncomfortable truth that most growth hires don't want to hear - and that most founders don't explicitly say - is that those first 90 days reveal whether you understand how to build compounding systems or whether you're just a bag of tactics looking for a place to land.

I've been on both sides of this. I've been the growth hire who got it right - who spent the first month doing things that looked slow but paid dividends for years. And I've been the growth hire who sprinted into campaigns too early, got some quick wins that didn't compound, and found myself six months later still unable to explain what was actually driving the business. The difference wasn't intelligence or work ethic. It was approach.

This piece is the playbook I wish I'd had for my first growth role. It's built for three audiences:

Let's get into it.

---

Before we dive into the 90-day playbook, we need to address the elephant in the room: nobody actually agrees on what "Head of Growth" means.

I've seen the title applied to someone who runs paid acquisition and reports to a CMO. I've seen it applied to someone who owns the entire customer journey from first touch to expansion revenue and reports directly to the CEO. I've seen it mean "the marketing person at a company that doesn't want to say marketing" and I've seen it mean "a product-minded operator who happens to care about distribution."

That's a mouthful, but each word matters:

• "Strategy and execution" means you're not just coming up with ideas - you're accountable for making them real
• "Acquires, activates, and retains" means you care about the full customer journey, not just top of funnel
• "Scalable" means you're building systems that compound, not just running one-off campaigns
• "Measurable" means you can actually prove what's working

This is distinct from adjacent roles in important ways. A VP or Head of Marketing is often more brand and awareness-focused, particularly at larger companies - they might not own activation or retention at all. A CMO is typically a broader executive role that encompasses brand, communications, PR, and marketing operations, often with less hands-on experimentation. A Product Manager owns the product experience but usually not distribution or acquisition channels. The Head of Growth sits at the intersection of all of these, which is why the role is so hard to hire for and so easy to misdefine.

At an early-stage startup - Seed through Series B - the Head of Growth typically needs to be a generalist with an unusual combination of skills:

---

I've tried various frameworks for structuring the first 90 days, and the one that's consistently worked best is what I call Model → Measurement → Motion.

Model (Days 0-30) is about understanding how the startup actually grows - not how the pitch deck says it grows, not how the founder hopes it grows, but the real mechanics of how customers discover the product, why they sign up, what makes them stick around, and what makes them leave. The deliverable is a clear, simple growth model document and a baseline understanding of your funnel metrics.

Measurement (Days 30-60) is about making growth legible to the entire company. Most startups I walk into have a measurement problem masquerading as a growth problem - they're flying blind, making decisions based on gut feel, last-touch attribution, or whatever metric the CEO happened to glance at in a board presentation. The deliverable is a single source of truth dashboard that people actually look at and a growth review ritual.

Motion (Days 60-90) is about converting understanding and visibility into action that compounds. You've earned the right to ship because you understand the model and can measure results. The deliverable is a prioritised experiment roadmap, concrete shipped work, and at least one measurable improvement you can point to.

---

The first 30 days are about one thing: learning faster than anyone expects you to.

You're not here to "make quick wins" yet - that comes later. You're not here to launch campaigns or redesign landing pages or spin up new channels. You're here to understand the growth model better than anyone else at the company. This understanding is the foundation that makes everything else possible. Skip it, and you'll spend the next year building on sand.

The reason this phase matters so much is that every startup grows differently, and the generic playbooks that work at one company will fail spectacularly at another.

The Week-One Growth Audit

The first two weeks should be an intensive discovery sprint. Here's my structured process:

Synthesising Into a Growth Model

All of this discovery should synthesise into a simple document - one or two pages - that captures how the company grows. Aim to have this done by Day 30.

The Day 7 CEO Memo

The founder will either validate your hypotheses or push back on them. Both outcomes are valuable. If they validate, you've confirmed you're on the right track. If they push back, you learn something important about how they see the business.

---

The second phase is about measurement, and it's where many growth hires get impatient and make mistakes. You've done your discovery. You understand the business. Now you want to do things.

Here's why you resist that pressure:

Experiments without measurement aren't experiments, they're guesses. You can launch ten campaigns in the next 30 days, and if your tracking is broken, you'll learn nothing.

I've lived this. Early in my career, I joined a startup and immediately started running paid acquisition experiments. The campaigns looked like they were working - cost per signup looked great, we were acquiring users. Six months later, we discovered our attribution was completely broken. Most signups we'd attributed to paid were actually coming from organic. We'd wasted significant budget scaling a channel that wasn't actually performing.

The State of Data at Most Startups

Let me paint an honest picture of what you'll typically find:

Event tracking is inconsistent. Attribution is either missing or dangerously oversimplified. Cohort analysis is rare. Data freshness varies wildly. And definitions are fuzzy - ask three people what an "active user" is and you'll get three different answers.

Your job in Days 30-60 is to fix enough of this to make growth legible. Not all of it - but the critical gaps.

What to Fix First

The Growth Dashboard

By Day 60, you should have a single dashboard that shows the health of the growth engine at a glance. One source of truth, not five different dashboards showing five different versions of reality.

The dashboard should be scannable in under a minute. Include:

• Acquisition: Volume of visitors, signups, leads by source. Week-over-week trends.
• Activation: Conversion rate from signup to activated. Time to activation. Drop-off points.
• Retention: Cohort retention curves at week 1, 4, 8. Month-over-month trends.
• Revenue: MRR/ARR, new vs expansion vs churn. CAC and LTV if calculable.

Establishing the Growth Review

A dashboard nobody looks at is just decoration. Establish a weekly growth review, typically 30 minutes:

---

You've earned the right to ship. You understand how the business grows, you can measure results reliably, and you've built credibility with the team. Days 60-90 are about converting all that preparation into motion that compounds.

Designing an Experiment Backlog

I use a simple ICE framework for prioritisation:

Score each dimension 1-10 and multiply. It's not scientific, but it forces explicit trade-offs.

For the initial backlog, focus on three categories:

Shipping Your First Experiments

Aim to ship 2-3 meaningful experiments in Days 60-90. "Meaningful" means connected to your growth model, properly instrumented, and documented.

Documenting and Communicating Results

Every experiment needs written documentation: hypothesis, design, results, learnings. This creates institutional memory and holds you accountable.

“We tested whether adding social proof to the pricing page would increase plan selection rates. It didn't - the variant performed 5% worse. Our hypothesis was that social proof would increase trust, but users at this funnel stage already have trust. We're pivoting to simplify plan comparison instead.”

---

I want to address quick wins directly because I know the pressure is real. You want to prove you were a good hire. The CEO wants movement. But chasing the wrong wins creates long-term problems.

A good quick win strengthens the system. A bad quick win bypasses it.

The litmus test: "Will this quick win help us learn something that compounds, or is it just a number we can point to?"

---

The first 90 days are as much about building trust as driving results. You need to build credibility with different stakeholders who care about different things.

Credibility with Founders/CEO

Credibility with Product and Engineering

Instead, lead with user insight: "I talked to 20 churned customers and found the most common friction point is the project setup flow. Here's the data showing where drop-offs happen. Can we talk through solutions together?"

When you do make requests, make them well. Write clear experiment specs with hypotheses, success metrics, and implementation considerations. And deliver on your promises - if an experiment doesn't work, be honest about it.

Credibility with Sales and Customer Success

In the first 30 days, listen to at least 10 sales calls. Take notes on what prospects ask, what confuses them, what objections come up. Create a simple document summarising what you've heard and share it with the team.

---

Fractional and Part-Time Growth Leads

Interim Growth Leaders

First-Time Growth Leaders

---

For growth candidates evaluating an offer, align on these points before you start. Misalignment here is the most common reason growth hires fail.

---

Let me close with something rarely made explicit: the first 90 days are a mutual evaluation.

If both sides hold up their end, you get a partnership that can actually drive growth. If either side falls short, you get the all-too-common pattern: a growth hire who's gone in 12 months, a founder who's convinced "growth people don't work here," and a company no closer to solving its acquisition problems.