I used to advise people to go work for an existing company for a few years before trying to start their own, but I now think that was bad advice. It's true that you learn things working for a big company, but you learn more, faster, starting your own. A lot of people we've funded have said they wished they'd quit their corporate job sooner. I don't remember any saying they wished they'd stayed in it longer. The one p…
If I had to advise people, I'd say "It's time to do a startup when you have more trouble concentrating on your job because you're distracted by your startup idea than you have trouble concentrating on your startup because you're distracted by your job." That comes at different times for different people, and it's not uncommon for someone to bounce between the two of them multiple times during their lifetime. Above all, I don't think it's a binary choice: it's silly to think in terms of "I'm a startup person" or "I'm a big company person", you should evaluate every opportunity available to you on its own merits rather than relying on your preconceptions of what you think it'll be like.