Planner: choose a start and end date (example: blank days)

Selem aleykoum wa rahmatullah.

Is it possible to write down tasks to be done on a monthly basis or date of your choice to do tasks and not weekly? Let me explain, I wanted to be able to "schedule" a reminder for white days in order to fast on those days. The same would apply to other important dates for which fasting is recommended. But at the moment, I can't choose specific dates for this.