I've got a table of customers and purchase dates, and I'm trying to figure out in any given month, whether that customer is a new (registered but not purchased) or repeat customer (purchased in this month or any prior month.) I'm really having a hard time trying to figure out how how to run the iterative calc.

RegMth CustomerName OrderDate New or Repeat?
Jan Customer A n/a
Feb Customer B 20-Feb
March Customer C 4-Mar
March Customer B 11-Mar
March Customer C 24-Mar
March Customer D 12-Mar

Can someone please help advise?

repeat visitor analysis.xlsx