If your mind is on your startup, partying, or you don't know what you want to do, I think you'll regret not having the focus and direction you could have put toward college by waiting. Experiencing a couple of failed startups or working a crappy job can really motivate you to put 100% into school. In my case, I became an airborne paratrooper right out of HS, grew up (alot), got $$$ for college, then hit the ground running.