I work for Target. # of trucks depends on the size of the store. a Super Target might get 2 trucks a night, but a small Target may only get 4 trucks a week. There are no specifiic schedules for when we get certain merchandise, and we can't see whats on a truck until right before we unload it. Even then, we can't (shouldn't) let guests know whats on the truck before it hits the shelves. I remember last year we had 20 or 30 calls in the middle of the night (even though our phone message says we're closed) by people asking about wiis', elmos, PS3's etc. Its really hard to get merchandise on the shelves when we keep having to stop and answer the phone at 3am.
Oh yeah, and unfortunately, Target and Target.com are practicly 2 separate entities and we don't get information on online availability. We do have access to Target.com at the registry kiosks at the front of the store, and Guest Service Team Members will be happy to help you look stuff up online. The 'availability' lookup option online is only an estimate and doesn't update immediately. Keep calling your store and eventually they'll get it in. You could also call Guest Relations w/ the DPCI (found online) and they can help you find it.