How to do : Paying the goods before receiving ?

What I do, is add two additional lines to the Purchase order, one to a clearing account say 195 for the total amount of the invoice, and a second line with a negative one to the same clearing account. I then receive and invoice the first entry to pay the vendor, and then when the goods actualy arrive I receive the remainder of the Purchase order. all the items and the one negative entry. this reverses the prior entry to the clearing account, and records the inventory, and a zero dollar vendor invoice to close out the PO. Just an Idea, it works for us David