Three years to startup
raffi: I read some of the comments and others have probably said what I'm going to say.  I wanted to startup too but due to other obligations (coughmilitary servicecough), I couldn't do it until I was...  get this... 27.  So I know how you feel.  It's weird to watch friends do things and be successful and feel like you have to wait until your turn.Every year I wanted to create something I called a cyber lemonade stand.  Tim Ferris calls these muse businesses.  I call it something simple where I charge money, people pay me, and I learn that I can do it.  This is a big confidence builder and something you can start doing right away.  http://www.feedbackarmy.com was my cyber lemonade stand, After the Deadline http://www.afterthedeadline.com was my startup.What I find interesting is that I wasn't willing to take the steps towards the lemonade stand until I was out of the Air Force and had no job.  If you're serious about starting up though, I really recommend you start on this concept right away.  A small project will let you experiment with the things necessary to get something off the ground (contacting bloggers to generate PR, hiring out small stuff you can't do well yourself, etc).Once you hit that magical time when you can startup--go for it.  But you're thinking the right way trying to get some training in before the big race.