FOC (Final Order Cut-Off) is the acronym used in the comic/hobby industry for letting you guys know when we, Fandom Comic Shop, have to have our orders into the publisher or manufacturer.  As long as we can get our order in before the FOC then the publisher/manufacturer will be able to fulfill our order. 

If you place an order for an item that hasn't released yet but it is past the FOC, then your order may be allocated.  We do our best to ensure we have plenty of stock for you guys, but in some instances when we place an order past the FOC our order won't get fulfilled by the publisher/manufacturer (this is especially true for comics).  If we determine we cannot fulfill your order, you will be refunded in full.

In short, if you want to ensure you get your FOC pre-order item, then make sure to get your order in before the FOC.