Currently we create a proforma so that we could send an invoice to a customer in order to receive payment before the items ship.  However, we are not posting these proforma invoices.  We receive the payment and it sits on their account until the product ships and an invoice is created, and then the payment is matched up to the invoice.  What I am wondering, is what is the proper flow if a proforma is created to where it can post and tie out to the payment and the eventual invoice?