I would agree on the earlier date as implementation inevitably lags behind documentation.
The use of IRR paints is fully descibed in Materiel Regulations for the Army Vol.2, Pamphlet No.3 Painting of Army Vehicles, Aircraft & Equipment. December 1980. It superceded the previous version of 1975 which makes no mention of IRR paints. What I never knew was whether an ammendment had been issued between these dates, presumably not, given what AFTM has said.
(Jerry I'll have you dancing with bananas when I see you next).