The first hundred days will either build your startup’s backbone or set you up for a slow collapse. Forget the glossy pitch-deck stories. In the real world, those first three months are where you either get the boring, unsexy work right or you spend the next year cleaning up after yourself. I’ve watched founders lose deals over a missing EIN, and I’ve seen promising products die because payroll taxes went ignored.
Days 0–30: Get Your House in Order
Formation is not a paperwork chore. It’s the legal spine of the company. For U.S. startups chasing venture money, that usually means a Delaware C corp. The Delaware Division of Corporations has made it almost frictionless, but you still need to file the certificate, appoint a registered agent, and lock in your Employer Identification Number with the IRS. Skip it, and you can’t open a bank account, pay employees, or even sign certain contracts.
Speaking of banking, separate your money from the company’s on day one. The SBA warns that co-mingling funds can break liability protection. While you’re at it, register for state and local taxes. If you need permits or licenses, apply now not after a customer asks for proof.
Security and compliance don’t wait for product launch. MFA on all accounts, encrypted devices, basic privacy policy none of these are optional anymore. NIST’s guidance for small businesses is clear: treat cybersecurity like a seatbelt.
Days 31–60: Build the Thing, Protect the Thing
This is when founders start sprinting toward MVP. But a “minimum viable product” is not code for sloppy work. Harvard Business Review’s lean startup playbook calls for validation first customer interviews, problem confirmation before writing a line of code. By the end of this window, you should have pilots in the wild, even if they’re ugly.
Protect your assets as you build. Check the USPTO database before you fall in love with a name. File the trademarks you’ll actually enforce. If you have defensible tech, think provisional patents. Copyright your original code. These moves don’t just protect you from thieves they show investors you’re serious.
Hiring often begins here. Verify work eligibility with Form I-9. Respect wage laws. Report new hires to the state. Get an employee handbook in place. None of this feels urgent until a wage claim lands on your desk.
Marketing groundwork happens now too. Define who you’re selling to, what you’re charging, and how you’ll reach them. FTC rules on CAN-SPAM are not a suggestion stay compliant before that first email blast.
Days 61–100: Ship, Sell, Measure, Adjust
Launch is not a party. It’s a pressure test. You’re rolling out to a real market, with real metrics and real customer expectations. Put a sales process in writing. Instrument your product so you can actually see what’s happening retention, churn, conversion. The 500 Global “pirate metrics” framework is a solid starter map.
If fundraising is on the table, now is when you clean the data room. Cap table, IP assignments, contracts, financials. Investors don’t like surprises. And if you’re raising with a SAFE, use the standard terms.
This is also when cracks show in operations. Vendor contracts that never got reviewed. Backups that don’t actually restore. Customer support that’s just “send us an email.” Fix these before they scale into disasters.
Accessibility matters here, too. WCAG 2.1 AA standards aren’t just for compliance they’re for customers who can’t use your product otherwise. And if you’re shipping an app, Apple and Google both have rules that can reject you outright.
The Mistakes That Kill Startups Early
CB Insights’ post-mortems read like cautionary tales. Most failures aren’t about competition they’re about making something nobody wanted. Second place goes to running out of cash. Third to team meltdowns. The fix is boring but effective: keep validating the market, track your burn, and put founder agreements in writing. Vesting schedules and clear roles have saved more than a few partnerships from implosion.
A 12-month runway model is not overkill. Track customer acquisition cost, lifetime value, and gross margin. These numbers will tell you if you’re heading toward profitability or just buying time.
A Real First-100-Days Rhythm
The veterans break it down like this:
- Days 0–15: Form the company, get the EIN, open the bank account, start licenses.
- Days 16–30: Payroll live, insurance locked, security baseline in place.
- Days 31–60: MVP defined, pilots live, marketing assets running.
- Days 61–100: Public launch, sales engine humming, investor-ready if needed.
Miss the rhythm, and you’ll spend the next quarter chasing your own tail. Nail it, and you’ve got a foundation sturdy enough to survive the next hundred days which will be just as intense as the first.
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Nina is a researcher and culture curator from NYC who spotlights transformational books, podcasts, and ideas for entrepreneurs.
