Assign dynamic Flags for months

I have data from 2020 Jan to 2025, I would like to give flag by month wise if it is current month 0, other months in same year or previous months or futures months according to current month flag. If we consider March as a current month now, it should how flag as 0 for future or past month it should show as below. Please help me

ex:  DD/MM/YY

       01/12/2022    -3

        01/01/2023    -2

        01/02/2023    -1

        01/03/2023      0