A team has 10 minutes grace period in which to be ready to play, after the scheduled game time.  In the event of a field change, the visiting team should be given an additional grace period to be determined by the referee.  The minimum legal number of players to start a game is 7 players.

The grace period is not intended to be used to fill your numbers from 7 or 8 players to a full roster,  If you have 7 players at the scheduled game time, then the referee is instructed to start the game on time.