lol...
it varies for each couple. my brother and his wife have dated since they were 15, and got married when they were 19 or 20, and they are as happy as can be.
me, i'm 31, had four different fiancees' and finally got married last fall.
do what feels right. my advice is to make sure this person is your best friend. i know it sounds sappy, but you're spending the rest of your life with her. you sure as hell had better enjoy hanging out with her and doing nothing.
good luck, and congrats!
