Hi, Anyone can help to solve my problem please?

I want to create a lookup formula that can return the result of date which a
particular product will out of stock based on customers order. Please refer
to table below. I have 55,000 Screw AB left in finish good store. Based on
actual customers PO, I can support customers demand until 5-Jan-07, stock
is not enough for 6-Jan-07 delivery . Is there any lookup or other formula
that can tell me the date? I have many items to check weekly, Really
appreciate that someone here can help to ease my problem.

A B D E
1 Part name stock Delivery date PO QTY
2 Screw AB 55,000 1-Jan-07 12,000
3 2-Jan-07 10,000
4 3-Jan-07 10,000
5 4-Jan-07 10,000
6 5-Jan-07 10,000
7 6-Jan-07 10,000

Formula : ?

Thanks in advance.
Good day.