A. Advertisements can be made optional, giving users the option to install the app/update/OS, or mandatory, which means the program associated with the advertisement will execute. You can configure mandatory assignments to be mandatory immediately—meaning it will activate as soon as clients see the advertisement—or a schedule can be defined through the Schedule button. If you select the Schedule option, you can set a recurrence for the advertisement that will re-advertise to clients on the schedule defined, as shown here.

SCCM Schedule