Sourcing Rule based on Requisition Creation Date and not Need-by date

How can a Requisition pick the sourcing rule / BPA based on creation date and not need-by date?

Let say the following:

·         lead time for item xx-01 is 30 days

·         item xx-01 is min-max planned

·         ASL, Assignment set exist for the item with the following sourcing rule:

o   From July 1^st to July 31^st take supplier Hewitt and BPA 1005

o   From August 1^st to August 31^st take supplier Sandvick and BPA 1009

Scenario:

Today July 4, I run the min-max and import the requisition. Because of the long lead time (30 days) the Need-by date onto the requisition is in August. Hence, Oracle selects Sandvick and its associated BPA.