Early 66 Cuda/ Valiant badging in 1966

Timing is tough. The dealer brochures are not dated, but have the barracuda emblem

Owner manuals do give a clue
1st edition July 1965 doesn't have barracuda club
2nd edition October 1965 has the barracuda club with the depiction of the barracuda emblem. Based on that, the emblem took place around this time. And of course based on stock on hand at the assembly plant.

And don't forget the rear window emblem