Upload & Sell: Off
I don't mean to discourage you, but I think Amazon gives everyone that date, fulfills however many orders they can get, and then puts out a new date for their remaining orders. After all, they have no idea how many cameras are coming to fulfill their orders.
I was one of those folks who Amazon gave an initial date of March 21st, then you receive the e-mail stating your order cannot be filled and they will notify you soon regarding a new possible delivery date.
So until you see that "shipping soon" message attached to your D4, you really have no idea when you are going to receive your camera.
I wound up purchasing a D4 locally rather than waiting for Amazon, Adorama, or B&H to finally figure out exactly when they would receive any D4s.