Invoice date vs Shipment date

I think the sales can be recorded on any of the two dates, as per the requirement of the buyer or the seller.

But the invoice date is more feasible to record the sale transaction.

You have to give both the details of Invoice and shipping bill in Table 6A of GSTR1  , for i.e  Invoice Date , Number , shipping billing number and date , port code ,  invoice  value , IGST  etc  just check in table 6A of GSTR1

I think you can file  before 11-1-22 last date of GSTR1 filing .