Then you announce the participants earlier. Not on the day of the tourny because i never said that. plus then only the people who are registered will be the people training level 30's for this tourny...
or just have as many people sign up in one day as possible. then randomly pick 32 contestants. doesnt have to be one day. doesnt have to be 32. but randomly picking the participants reduces the need for timezones. just a suggestion :)