Reconciling Current Inventory Status

Fist time poster... please forgive any lack of knowledge....

we're looking for a simple method that will allow us to 'commit' inventory to an order to be fulfilled in the future without causing our warehouse to filter an extra layer of inventory information.  The idea is to 'allocate' parts of our inventory so that large-scale orders that are submitted by large-scale customers can be fulfilled on time and on the date requested.

Currently, if we click to 'approve' an order it's automatically sorted to a 'fulfillment' status where the warehouse pulls and ships the items asap.  the problem here is that large orders have to be 'approved' at a later date than they are submitted, thus that inventory isn't necessarily allocated to that order.