By the time you're at your YC interview, you already know all of the terms of the deal except for one variable: the percentage of the company taken by YC. So if

By the time you're at your YC interview, you already know all of the terms of the deal except for one variable: the percentage of the company taken by YC. So if you're accepted, PG calls and gives you this one piece of missing info, and you and your cofounders get 5 minutes to decide whether it's acceptable.