A quick fix for now is to have 2 watering times. For example for @wakeX2 time for your 1st Schedule watering would be @4am and make sure to only include the zones for enough time to finish watering by 6:30am the latest. Then create the 2nd watering schedule to start at 7:30am watering the remainder of your zones to finish up watering for the day.
I have setup my sprinklers this way. For mine I don't want the sprinklers to water between 6:30am to 7:30am. So I set mine up to start watering zones 1 thru 3 at 4am which end prior to 6am, then I setup another schedule to water starting at 7:30am to complete watering the remainder zones 4 thru 8.
Maybe this will work for you as well.