A quiz: Initially D&D used 3d6-in-order to roll ability scores. Later it switched to 4d6-drop-lowest-any-order. To your recollection, when did that rule first appear in the D&D core rulebooks?
I know its in 2e (since it was method IV on the Core Rule's program) but It might be in some 1e book (DMG?) first. It didn't become "default" until 3e though...
I think the absolute latest it could be is 1e Unearthed Arcana -- they had a bunch of different stat-rolling systems in there. I remember stuff like Barbarians rolling 9d6 and taking best 3 for Strength, or something like that.
I first read it in Unearthed Arcana, which had a whole section on alternative character generation methods. It is probably in an earlier Dragon article, but I don't have time to check.
I know that it appears in the 1e DMG, but nowhere at all anywhere in BECMI. I don't remember ever seeing any alternate character creation rules in OD&D, but I'm not too familiar with Gygax's supplements, so I wouldn't bet on it being in I: Greyhawk, but it *might* be. Anyhoo, my educated guess is 1e.