1983.I believe D&D orcs were first green in the 2nd edition monster manual 1993. Warcraft came out in 94. However, Warcraft was an unlicensed Warhammer game, and Warhammer had green orcs since the early 80s, and is almost certainly the original source for the green WoW orc look.
There is the slight wrinkle of Star Wars gammorians, also from 1993, who closely resemble 1st edition/Basic orcs and are decidedly green.
There are WWI propaganda posters that depict German soldiers as pig-like and grey skinned, these are likely the original source for the orc look.
Sure, Gammorians are in there somewhere.
I find it interesting that for the Lord of the Rings movies, Jackson went with a very traditional goblin look for Moria orcs, but not the "D&D orc" for the rest.

