Start a business and your first 90 days are a hunt for demand. Buy one and your first 90 days are a job protecting demand that already exists. Same window, opposite mistakes — and most new owners prepare for the wrong fight. This week Josh and Mike lay out both playbooks side by side: how a founder should prove product-market fit instead of feeling it, why the manual work that doesn't scale is the work that matters, and why the median small business has just 27 days of cash to get it right. Then the other side: what a new owner should do (and absolutely not do) in the first 100 days after close, how to keep the key employees and customers you paid for, what the seller should still be doing for you, and the cash controls to install in week one. Build it or buy it — the business world is heating up!

Hot takes:

• Starting a business is a hunt for demand; buying one is a job protecting it. Founders need to move fast, buyers need to move slow — and most people bring the wrong instinct to the window they're in.
• Product-market fit isn't a feeling. If fewer than 40% of users would be “very disappointed” without you, you don't have it yet — Superhuman went from 22% to 58% by treating that number like a KPI.
• The median small business has 27 days of cash. That's not runway, it's a ledge — spend like you're broke until customers prove otherwise.
• 47% of key employees leave within a year of a deal. If you just bought a business, your first hire is keeping the people you already have.
• In the first 100 days after close, the smartest thing a new owner can do is change almost nothing, meet everyone, and control the cash.