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

The earliest SPD I have registered is a BH23H 2/27/67. They start rolling out after that pretty steadily. I have one I purchased from original owner. He purchased it in early December 1966. The spd on it is 3/28/67 and IBM is same. He took delivery about a week later.
1967 383 FS Fastback 03031967