If you’ve just landed a Head of Finance, Finance Director, or CFO role at a startup, the clock’s already ticking as you hurtle towards the end of your probationery period.

And while the first three months in the job can feel like a whirlwind of board meetings, broken systems, and missing reports, this is actually the most critical window to set yourself up for long-term success.

When I left a role as a Finance Director, my CFO gave me one simple recommendation before starting my next role, read The First 90 Days by Michael Watkins.

Best advice I’ve ever received.

Yes, the book is aimed at C-suite executives and senior leaders, but if you’re moving into your first finance leadership position, especially in a fast-moving startup, this book will give you structure, strategy, and a much-needed sense of control.

Here's why it matters and how to apply the lessons as a startup finance leader.

Why Your First 90 Days Matter So Much

When you join a startup in a finance leadership role, there’s a lot to absorb and fast. From unpicking messy numbers to figuring out who actually owns what, those first few weeks can easily turn into reactive firefighting.

But that early period isn’t just about survival, instead it’s your opportunity to:

• Build credibility quickly
• Establish trust with founders and teams
• Spot where you can add the most value
• Avoid getting stuck in the weeds

Watkins talks about reaching your break-even point, which is  the moment where you're contributing more than you're consuming.

The faster you get there, the better.

But you need a plan.

Key Takeaways from The First 90 Days (For Startup Finance Leaders)

1. Get Clear on Quick Wins — Then Deliver Them Fast
   
   Start by asking: What are the low-effort, high-impact things I can fix now? 
   
   Maybe it’s upgrading the management accounts format.
   
   Or cleaning up a cash forecast that’s been off for months. Or implementing a simple tool to track burn. 
   
   In a startup, these things get noticed. And they buy you trust.
   
   At the same time, start mapping out your longer-term value plan. What’s your 6-month roadmap for finance?
   
   
2. Build Relationships Before You Need Them
   Finance touches every part of the business but not everyone wants to talk to finance.
   
   Your job is to change that.
   
   In the first 90 days, focus heavily on stakeholder mapping. Who are the decision-makers, influencers, blockers, and sources of knowledge?
   
   That includes:
   - Founders and co-founders
   - Sales and ops leads
   - Product heads
   - The board or investor reps
   - The outsourced bookkeeper
   
   Get into regular comms rhythms, listen more than you speak, and figure out how each person likes to work. Especially your CEO.  You want to learn how they prefer to be kept in the loop, and come prepared.
   
   You’re not just here to build reports. You’re here to build trust.
   
   
3. Understand the Vision.  Then Align Everything to It
   Startups are often running fast, but not always in a straight line.
   
   Before you start rewriting budgets or questioning spend, get really clear on the bigger picture:
   
   - What’s the founder’s long-term vision?
   - What’s the company’s current operating model and strategy?
   - What are the real KPIs that matter right now and what’s just noise?

Once you know that, you can better prioritise your work. Instead of reacting to every fire, you can focus on the changes that help the business scale.

The First 90 Days gives you a framework to follow but you still have to adapt it for startup life.

Your role isn’t to get everything perfect out of the gate. It’s to make smart choices, build strong relationships, and put finance in a position to lead not just report.

So if you’re starting a new role, or planning to, grab the book, skim the chapters that resonate, and use it to design a 90-day plan that sets you up to succeed.

Want more practical recommendations? Check out my full list of finance leadership book picks here.

Want to become a confident, strategic finance leader in a startup within the next 12 months? 

Here’s your plan:

1. Subscribe to my YouTube channel for weekly practical tips and real talk about startup finance leadership.
2. Read my book Financial Leadership Fundamentals to get clear on what’s expected of you and how to show up as a leader.
3. Join the Financial Leadership Fundamentals course to fast-track your growth with structure, support, and strategy that works in the real world.