Change Lesson Time Automatically

I have a speadsheet with a column of student names with corresponding columns of classes and class times. The class times are on a rotating schedule and will be35 minutes later every week. Groups A to D have rotating lessons at 8.55, 9.30,10.05, 10.40 and groups E and F have rotating lessons at 11.45 and 12.20. I need to print slips with student names and class times each week. I want to be able to update the lesson time for the next week automatically. The only way I have thought to create a custom sort list with lesson times and I drag and fill series for new lesson times. However, the list doesn't return to the beginning of the series, it creates a new lesson time. My question is, is there a better way to update the lesson times?