Some times, the schedule must be shifted earlier in the period. This can be done in two ways, either to move the entire remaining schedule earlier, or to open up a gap in the middle of your schedule. The cell menu reflects these possibilities
Moving Entire Remaining Schedule
To move the entire incomplete schedule, we must bump from the end of the period. Select the menu option bump schedule earlier from end of period. This is the equivalent of navigating to the last planned date for the selected course and student, and bumping earlier.
Opening a gap by Shifting Earlier
To open up a gap at any point in the schedule, navigate to the date to become empty, and select the menu option bump schedule earlier from this date. This will push the incomplete schedule backward from the selected date only.
Note that in either case, the bumping behaves according to the bumping criteria. If your bump does not carry forward as far as you expect, your lesson schedules likely do not match.