I didn't start my first business until my early 30s and found the mix of energy and experience just perfect (much easier, in my case, than it likely would have been in my 20s). Try to avoid the "wasting the prime of my life" argument -- one way or another, that time is going to pass.

If you want to start a business and are ready for it, start it. If you'd rather do something else, do that instead.

You're not wasting time if you genuinely enjoy how it is being spent.