Apple always arranges the iPhone deliveries to an exact date. If your shipment were to get somewhere a day early they would probably put a hold on it to make sure it arrives on the release day. They compute a delivery day from china to make sure everyone gets their IPhone on the same release day as the stores. They want it to hit all at once.
that's great and all, but with 1mm+ orders going out, some will definitely get delivered earlier, just like they have in the past.