gringo: Why not seed the tournament and give the higher rated players a bye? Then the next round would start with a power of two number of players. Simple solution and it will get every tournament of the single elimination type started on time.

16 player tournament, but only 11 sign up. The deadline passes. Now you take the player's ratings and pair them up to add to 17 as they're ranked. 1-16, 2-15, 3-14, 13-4, 12-5, 11-6, 10-7, 8-9. As there isn't any players numbered 16, 15, 14, 13, or 12 players 1, 2, 3, 4, 5, would get a first round bye. Round two would start with 1 versus winner of 8-9. 2 versus winner of 10-7, 3 versus winner of 11-6. 4 versus 5.

The first round in a 11 entrant single elimination tournament would have three games played amongst the lower rated seeds. The three winners would continue on and the second round would have four games with the eight remaining players.

This can done for any number of entrants, odd or even. After one round the power of two number of people are left in the tournament and it will always work out at the end. Fencer should look into doing this. The tournament creator could have a 32 player tournament with 21 entrants and just have it start when the deadline passes.

I believe a few people posted earlier on this site about how brackets and seeding work. It's a real simple process.