As you move to a dual Sunday School schedule, here are some time schedules I have seen work:

9:30 SS/Worship, 11:00 SS/Worship (30 Minute Window for turnover/fellowship)

8:15 Worship, 9:30 SS/Worship, 11:00 SS/Worship (8:15 added to allow more space in 11:00 Worship service)

8:00 SS/Worship, 9:15 SS/Worship, 10:45 SS/Worship (Heaviest schedule I have been a part of where we had ABC Sunday School hours.)

I have also worked with 7:00 and 7:30 “early bird” Sunday School classes, which have been Senior Adult, or men’s classes.

Whatever the schedule adjustment, communicate clearly and for some time about the changes.  Pray about it, and have fun!