I had no idea what percentage to ask for. I asked a few friends who had been in startups, and that convinced me that the 1% I was being offered (over 5 years) was a good deal. What I didn't realize till about a year later was that my friends had all joined their respective companies as, say, employee #20 or #30. I was coming into a company with zero employees, and it turns out that I should have been pushing for on the order of 5x was I was being offered.

OTOH, I did tell Jeff that I was having a daughter in several months and planned to go to a 3 day week after that happened. He agreed to that ("I knew when I met you that you'd think about work 24/7 anyway"), so there was a tradeoff there.

I'm not really complaining, but when I did find out what some other early hires had negotiated, it stuck in my throat for a bit.