Sorry, didn't mean to be hasty. In _my_ experience with ~150 transactions, it's never taken more than 30 seconds. In fact, I'd bet 1BTC it's never taken more than 10 seconds, for me.
With that said, I am sitting on a 20M downstream connection on a dedicated bitcoin machine running no other processes.
Your mileage may vary. Results represented here are not typical. Stunts performed on a closed course by professionals. Do not attempt. No animals were harmed during these transactions, blah, blah, etc.