I've asked before when the handoff happens to your local delivery people (from the drop-shipment from China or whatever), and no one has answered, so I'm guessing no one knows how the final staging really works.
When I had a pre-order for my MacBook Air, it was shipped from China standard FedEx shipping and took 2 days to get to my door. There was no specific launch day for that though.
The same thing happened with my iPhone 3GS pre-order. They didn't need to hold it for launch day because they timed it properly.