Need-by Date

Hi

We are on 11.5.10.2

We use minmax to generate requistions for purchased items.  We have, for example,  a 7-day lead time on the item. However, our supplier only ships one day per week. As a result, lead times must be long enough to cover the non-ship days. In most cases the shipment actually arrives sooner that the need-by date.

Is there any way to set the need by date dynamically (for atp purposes) based on the one day per week shipment?  For example, set need-by date to next available ship date + transit time.

Any help would be greatly appreciated

Thanks