Set off of GST liability against credit notes as per document date or as per ack date of IRN

Every month end we process credit notes for post sales discount. Say for the month of Nov 2020, discount will be processed on 4th December with posting date of 30.11.2020.

while filing the GSTR1 of Nov we will upload such credit notes and in GSTR 3B our tax liability will be adjusted against the credit notes and net liability is shown as tax payable by us for Nov 20.

However with the introduction of IRN for credit notes under E Invoice, credit notes generated on 30.112020, IRN will be generated in December 2020. Thus document date of my credit note will be of Nov 20 and acknowledgment date of IRN will be of Dec 20.
In such case, can we adjust credit notes of Nov against the liability of Nov or we have to adjust against the liability of Dec because IRN is generated in Dec 20

Please guide us in which month we can set off credit notes - Nov or Dec and why.