Monthly schedule by weekday

**Is your feature request related to a problem? Please describe.**
I want start calibration mode once per month on weekend.

**Describe the solution you'd like**
Set schedule to start calibration mode on first/last saturday every month.

**Describe alternatives you've considered**
Start calibration manual, start on specific day.

Version 1.21.1 have new great feature - schedule. I want to enhance schedule planner.