The first digit of the serial number is a country/region code. I has no bearing on the production order. Nikon will probably not sell 8 million D800s in the lifetime of the camera an certainly has not built any where near even 1 million to date.
Gary in SE Michigan, USA. Nikonians membership - My most important photographic investment, after the camera. D4, D810, D300 (720nm IR conversion), D90, F6, FM3a (black), FM2n (chrome) YashicaMat 124, Graflex Speed Graphic 4x5 My Nikonians Gallery & Our Chapter Gallery