Ideally, Quickbooks would have the feature to create an estimate, partially ship and partially invoice that estimate based upon quantity of product shipped when dealing with actual products.  Let's say my customer ordered 3 lamps and 1 piece of art.  The art is not in stock yet but they want the lamps now.  From the estimate one should be able to invoice and ship the 3 lamps while the 1 piece of art remains an estimate for later shipping and invoicing when it arrives in stock.  Very hard to keep up with what you have shipped or not shipped from a single order.  Partial shipments are ordinary business.