After escaping the army at 22 I went back to school and started writing. Short stories at first then a couple novels. My idea then was to be published before the age of 25 -- because I had read somewhere that some author I respected was first published at 25 (Clive Barker? Stephen King?) and of course I wanted to be a young hotshot.
I continued my pursuit of implausible careers with many years of studying philosophy, then roleplaying game writing. (By the way, I discovered that if you first pursue roleplaying game writing, then switch over to pursuing screenwriting, your family will actually be relieved.)
Today I turn 40. Being the clever sort, I had a backup plan in case the young hotshot strategy didn't work out:
Raymond Chandler -- published his first short story at the age of 42 and The Big Sleep came 6 years later. Not sure if there's a special term for old bastards so I'll just leave it as the old bastard strategy. One advantage of the old bastard strategy is that the older you are before you get published (or produced), the more impressive the achievement.