Recently I have run across customers that have several sales orders in Dynamics GP that will not be fulfilled and shipped for a few weeks or months. They are having problems with their inventory because the sales orders already have inventory allocated to the order eventhough the inventory is still on the shelf.
I have recommended that they look at creating a new Order Type. The new order type would not automatically allocate inventory items as they are entered on the order. Once the order is ready to ship you could then go into the Order and allocate and fulfill the items or you can allocate and fulfill when you transfer the Order to an Invoice.
I find many people forget about this setting in Sales Order Processing.
Tools - Setup - Sales - Sales Order Processing - Orders