The championship playoff to determine the D.IV teams that promote will finish up this Sunday (the 2nd game of the series is Saturday, with a 3rd game in needed on Sunday).
Then the draft happens. The draft is based on your current league, so pro/rel can't happen before that. Nobody plays any games next Tuesday which is when teams are being moved around, and schedules will generated.
Thursday a-week is an ordinary scrimmage date, and then the regular season starts on Saturday (May 10).