1967 Barracuda Formula S 383, what is the earliest date code?

Alaskan_TA said
Available from the start of the 1967 model year in 1966 - https://www.hamtramck-historical.com/images/dealerships/DealershipDataBook/1967/CCI05152011_00015 (983x1280).jpg

Yes I know, but I want a real world date as to when the first one's hit the dealerships.