Query needed to show ONLY first invoice against a customer

I have a customer who is trying to find when the first transaction against a customer related to the date the BP record was created.

All I need is the report is the OCRD Card Code and CreateDate then from OINV the DocDate

But I need to just show the earliest DocDate from the OINV table not duplicate records in the report for each invoice created.

Any help greatly appreciated.

Thanks

Dom