I have a suggestion. #1
For such non real-time games as we have here between players around the globe it can be useful to use somehow modified Round-Robin scheme. After sorting the players by theirs ratings and before distributing them among the groups to make "local" optimizing rearrangement (shifts) by the criterion - minimum of difference between players' time zones inside each group. This could speed up the first round as well as next ones (if this option will be applied to them too). I see "local" as constraints for that optimization shifts - this could be maximum allowed rating tolerance (for example inside +-50) or max allowed shift distance between more optimal and pure Round-Robin position (for example +-10% from number of groups: +- 2 for 20 groups, so one player from 7th group according to Round-Robin can be in groups from 5th to 9th after optimization) or both restrictions.
Addition: to ask players on joining the tournament to fill additional fields in their profile - preferable (or usual) time of day when the player will be on server. Time zone is not enough. Someone plays at work in the afternoon while another plays at home in the evening. So to use this more accurate time for adjusting the groups instead of simple timezone.
for BILL_5666: I am not a number! I am a free man! Yours is a human number: Five Thousand, Six Hundred and Sixty-Six.