Couldn't even guess how much time I have spent on this over my 43 years of 1st Gens. The two numbering systems [confirmation # and VIN #] are completely unrelated.
For 1969, both plants [Van Nuys and Norwood] were on the same system. My guess, the 1st confirmation # issued was 100001. Highest confirm I know of is in the 377xxx range so 277,000 orders were confirmed at one time. By the end of July '69 both plants had produced just over 200,000 Camaros so 77,000 orders were not built. In his book, John De Lorean stated dealer orders often contained errors; also dealers often exceeded allocations. Many orders were cancelled.
The confirmation # was assigned when Central Office determined the dealer order could be built within normal lead time. Orders that could not [usually material availability] would not be confirmed until the material was available. Under normal circumstances, not unusual to see consecutive confirmation numbers for a group of orders placed at the same time. Many, but not all, COPOs are like that
The confirmation number had nothing to do with production scheduling. The 50 Fred Gibb ZL1 Camaros were ordered at the same time; 49 had consecutive confirmation numbers 222001-222049. 1st car built [222002] December 30, 1968, 222001 was the 14th built on or about March 4, 1969. Last Gibb ZL1 order was built on or about March 24, 1969 [222044]. Some very early confirmations [105000-110000] were built in November.
I state 'on or about' because the last 6 digits of the VIN were assigned as the completed body assembly was received from Fisher Body. Bodies were then queued in the Schedule Bank and released to final assembly based on labor content to maintain line balance. VIN order was not a factor. 512345 may have released late on 2nd shift; 512340 may have been released the next day.
So what were the determining factors in when a dealer order was built? With two plants and 6,400 dealers ordering cars I'm sure the considerations were complex. Dealer status, location, equipment, paint color may have all been factors.