Overview
Proforma Invoices will print order shipments entries in an invoice format. The Proforma Invoice prints the shipping data and therefore, must be printed after entering new shipments but prior to processing those shipments. The Proforma Invoice never hits AR and you cannot receive monies against it, you will still need to create a regular invoice at some point. They are just so operations can send a financial record (albeit fake) along with a shipment.
...
Starting and ending Order number – you can choose an order or print a range of them, F9 will bring up a list of values and leaving the lines blank will print all available.
Invoice Date – Date that will print on the invoice this will default to the current date but can be changed.
Print Prices on Invoice – Checking this box will print prices on the Proforma invoice.
The Proforma invoice will not get an invoice number and if you need the company name on it you will need to check the "Company on Address" setup box on the AR customer Enter/edit screen. 
...