ASA says 1st pitch for Championship play.
USSSA says after the plate conference with coaches end....only thing I like about USSSA
Personally, I do the following. I set my timer for one minute more than the game time. That gives the home team (after the coin toss) time to get on the field and warm up. Usually the first pitch will be pretty close to the actual game time. Example...if game time is 1 hour and 20 minutes, I set my timer for 1:21 minutes. Start immediately after coaches meeting at plate. (I also tell the coaches that so they can hurry the players along).