You don’t have revenue yet. You might not have customers. You might not even have a product. But you have a plan — and you think you know what your business will look like.
Most founders in this position do one of two things: they build a pitch deck with a hockey stick, or they open a spreadsheet and start guessing. Revenue will be $50K in month one, $100K in month three, a million by year-end. Where do those numbers come from? Vibes. Ambition. What they think investors want to hear.
A Startup Business Engineering Work Session doesn’t start with revenue. It starts with the engine.
The Engine Every Business Runs
Every business — no matter the industry, no matter the stage — runs the same engine. I call it the Contribution Engine.
You have an audience. Some portion of that audience becomes customers. Those customers spend money. Some of them come back. What they spend minus what it costs to serve them minus what it costs to acquire them equals contribution.
Revenue minus COGS minus Sales & Marketing equals Contribution.
That’s it. That’s the engine. Two kinds of people work in every business: people in the engine (serving customers, attracting and retaining them) and people on the engine (instrumenting, financing, staffing, overseeing — the pit crew). To be profitable, contribution has to be greater than overhead. Everything else is overhead.
Most founders can’t see this engine because they’re looking at the wrong map.
The Wrong Map
The accounting system that runs the business world was invented in 1494. Luca Pacioli, a monk in Venice, documented double-entry bookkeeping. From that we got the Income Statement, the Balance Sheet, and the Cash Flow Statement. Five hundred years later, it’s still the standard.
The problem isn’t that it’s wrong. The problem is that it was designed to answer the wrong questions: Did anyone steal anything? How much do we owe the King?
It’s a map built for compliance, not clarity. Looking at your Income Statement to run your business is like driving a car by staring at the rearview mirror. You can see the damage. You can’t see the road.
What We Actually Build
In a Startup Business Engineering Work Session, we build a different map — the Integrated Financial Model. We start at the top and work down.
Start with the audience. Where will your customers come from? What channels will you use to reach them? How much will you spend? This is where most financial models skip straight to revenue. We don’t. We start with the work your team will actually do to find customers.
Convert the audience into customers. What’s your conversion rate? How many visitors, leads, or prospects does it take to get one paying customer? What does that first transaction look like — what will they pay, and what does it cost you to deliver?
Track who comes back. This is the number most founders ignore and most financial models leave out entirely. Repeat purchases are where businesses are made or broken. A 5% repeat rate and a 40% repeat rate are entirely different businesses, even if first-month revenue looks the same.
Build the unit economics. Now you can see the real questions:
- What does it cost to acquire a customer? (CAC)
- What do they spend? (AOV)
- Do they come back? (Retention → Lifetime Gross Profit)
- What’s the ratio of lifetime value to acquisition cost? (LTGP:CAC)
A healthy ratio is 4–6x. Below that, you’re subsidizing every customer. Above that, you should be spending more to acquire faster.
Then — and only then — do we build the income statement, balance sheet, and cash flow. Revenue isn’t a starting assumption. It’s an output of the engine. It flows from audience × conversion × AOV × repeat rate. Expenses flow from what it actually takes to run the engine and pay the pit crew.
What This Looks Like in the Room
It’s a working session, not a presentation. The founder and I sit in front of the model and build it together.
We start with questions:
- What do you sell?
- Who buys it?
- How do they find you?
- What do they pay?
- What does it cost you to deliver?
- Will they come back?
The answers go directly into the model. Not into a Word doc. Not into a pitch deck. Into a living spreadsheet where every assumption connects to every other assumption, and where changing one number ripples through the entire business.
By the end of the session, the founder has something they’ve never had before: a model that connects the work their team will do to the money their business will make — and the cash it will consume along the way.
This isn’t a financial projection some analyst made. It’s a map the founder built with their own hands. They understand every number because they put every number there.
Why It Matters Before You Have Revenue
Most founders think financial modeling is something you do after you have data. That’s backwards.
The model isn’t a report of what happened. It’s a hypothesis about how the business works. Pre-revenue is the most important time to build it because every assumption is exposed. There’s no historical data to hide behind. You have to say, out loud, what you believe:
- I believe I can acquire customers for $50 each.
- I believe 30% of them will buy again within 90 days.
- I believe my gross margin will be 60%.
Now we can test those beliefs. Not with data — you don’t have data yet — but with logic. If your CAC is $50 and your AOV is $40, you’re losing money on every first purchase. Your entire business model depends on repeat purchases. Do you have a plan for that? What if only 15% come back instead of 30%?
The model doesn’t tell you the future. It tells you what has to be true for the future you imagine to work.
The Size of Your Business
Here’s something most founders don’t realize: the size of your business is not determined by the size of your market.
Every founder says “we’re going after a billion-dollar market.” That’s fine. But your business doesn’t grow by capturing a percentage of an abstract market. It grows through specific channels — Facebook ads, Google, referrals, partnerships, cold outreach — and every channel saturates.
You spend $10,000 a month on Facebook and get 200 customers. You double the spend to $20,000 and get… 280 customers. Not 400. The channel is saturating. The cost per customer is rising. To keep growing, you don’t pour more into a saturated channel — you find a new one.
That’s the S-curve. Every channel follows one. And the unit economics, built the way we build them in this session, tell you the S-curve almost instantly. You can see it in the data before the marketing team admits it.
Healthy businesses maintain a portfolio of S-curves. That’s how you grow.
Only Twelve Things You Can Do
Once you can see the engine, you discover there are only twelve actions you can take to improve it.
Six growth levers:
- Widen the top of the funnel
- Increase conversion rate
- Accelerate funnel velocity
- Increase average order value
- Raise prices intelligently
- Drive repeat purchases
Four margin levers and two strategic: 7. Reduce cost of goods 8. Lower customer acquisition cost 9. Improve CAC payback time 10. Optimize channel mix 11. Segment customers by profitability 12. Model the S-curve and forecast capacity
That’s it. Those twelve levers control the engine. Every operational decision, every strategy conversation, every board meeting — it all maps to one of these twelve.
When a founder walks out of a Startup Business Engineering Work Session, they don’t just have a financial model. They have a language for running their business. They know the twelve dials they can turn, and they have a model that shows what happens when they turn each one.
After the Session
The model isn’t done. It’s never done. It’s a living system that gets managed weekly.
As soon as the business starts generating real data — the first ad spend, the first customers, the first revenue — those actuals replace the assumptions. Every week, the model gets a little more real and a little less hypothetical. That’s the feedback loop. Fifty-two times a year, you look at what actually happened versus what you said would happen, and you adjust.
If you aren’t managing your business weekly, you’re managing your business weakly.
John Zdanowski is the co-founder of Weekly Accounting and BrightZen. He has built five $100 million companies and a $100 million fund using unit economics and the Integrated Financial Model.