Automatic date slicer with conditions

Hello everybody,

I'm trying to figure out if it's possible to create an automatic date slicer that follows certain conditions.

Example:

If a new month begins and we have not yet reached 5 working days, the last day of the month before last should be selcted, beginning at the start of the year.  As soon as the 5 working days are reached in this month, the last day of the last month should be selected (and the past rest of the current year).

I thought about a relative date slicer, starting at the 1.1 of this year. But I'm not quite sure how I could filter the right end date.

greetings

Edit: Calculating working days etc. is no problem.