Upload & Sell: On
If they warranty started on the day it shipped to the dealer, which is idiotic, then Nikon would have to ask everyone for the dealer invoice any time there was a repair. They would not be asking for your invoice.
Putting that aside, generally the warranty starts on the day you have taken delivery of the gear, not ship date. So it's important to keep a record of the UPS, FedEx or other delivery tracking history. If only for those odd, infrequent times where something actually happens in that 3-5 day window on the tail end.