Apple sent an email telling people that despite what FedEx and Apple tracking said, they should expect in on the 23rd.In years past, FedEx held on to the packages so they'd be delivered on the 24th. Do we know that this won't be happening again this year?
Either way, if they can deliver the majority of those 600,000 phones a day early, that's probably at least 500,000 activations that will happen a day early, which will hopefully give people in the stores a better chance of getting in and out without any activation server issues (from too much volume).