I haven't seen this work. The majority of players are too stupid or uncoordinated to schedule a match and see it through with another player. The only ones I've seen work are MWarrior's and Masaru's, which had set times and the tournament was completed in one day, within 2 hours. Imo, announce a time for the tourney that you feel is reasonable to the most people, and just allow signups at that time. They pay half an hour before hand, you set up a bracket, and the tourney begins. Anything more complicated than that, due to experience from the past, probably will not be seen through.