Formula Needed for Transit Time

Good afternoon,

I have created a excel MRP for ordering raw material and I have listed below
the forumla I use, but I would like to add in the transit time which is 2 day.

Column E
A244 BRACKET Order 10000 10000 5000
NF Usage 11090 9050 7000
2000 PER BOX Inventory 10000 8910 9860 7860

>From the formula I have above I take the inventory and order two and halfs
weeks ahead which has the box quantity listed so I order in even amounts, but
I really need to add the transit time, can someone help me with this addition
of transit time.

Thank you,