Replay MTT games are cancelled if there are less than the minimum players at 2 minutes before the start time. We use that point as a reference because it gives the system time to allocate seats and prepare tables in order to get the first hand dealt at the Start time. If we waited until the actual Start time to decide if the game is going ahead, it would not start on time.
If it were to start with less than the minimum players, there is still no guarantee there will be any new players.
The registration period is 24 hours. We encourage people who are interested to play to register some time ahead and make sure the game has enough players to start, but the habit of waiting until the last minute or into Late Registration is not restricted to Royal games.