Ed, I understand the body numbers can vary widely. But how can a car with a 10A Tag have a VIN corresponding to VIN's from the 09A time frame? VIN 505520 is only the 5,520th Camaro thru the wall from Fisher to Chevrolet? By the end of Sep looks like 13,00 units or so were built or in production. It looks to me like the VIN precedes the Trim Tag?? Which I know it cannot.
The body number has nothing to do with when a car was scheduled/built. It was generated when Central Office confirmed [not received] a dealer order. VINs were sequentially assigned.
The date on the tag reflects the release of the order at Fisher Body. Body production usually, but not always, began shortly thereafter.
The best example of this are ZL1s #1 & #2. Orders 222002 & 222003 were confirmed on or about December 6, 1968. "Normal" production scheduling would have planned them for the first or second week January 1969, too late to prep for the AHRA season opener in PHX. N569358 & N569359 were expedited and final assembled December 30, 1968. 222001/N609238 was final assembled on or about Thursday March 6, 1969.
There are too many factors involved to speculate about production priority.