How did the term ‘buff’ originate

N00b and nub are corruptions of "noob", itself a corruption of "newb", short for "newbie". "Newbie" was in use at least as far back as the BBS era of the 1980s and early 1990s, where it referred to a user who was new to BBSs. It was less of an insult and more friendly than "noob", which was popularized by Counterstrike players in a context where a poor player can ruin the game for others.

Newbie itself is modern slang, where according to Wikipedia it referred to new soldiers in Vietnam. The word's origin before this is unclear, but it appears to be a word created to turn the adjective "new" into a noun, perhaps as a diminutive (Barbara -> Barbie, for example).

I think the phrase itself is older than World of Warcraft; certainly older than the Burning Crusade expansion. I remember seeing the phrase on Bungie fan sites during the Marathon and Myth heyday. For example, here's a post from 2001 on myth.bungie.org where Soon(tm) appears, and here is a page on the Marathon's Story website that contains the phrase all the way back in 2000 (you'll have to search the page for "soon(tm)" as it's a big page). Both of these predate WoW's announcement in September of 2001.

I would venture to guess that the phrase has been around almost as long as release dates have been left unannounced for popular titles, which is a very, very long time and may even predate the web (which is to say, you may need to dig through AOL discussion board or Usenet archives to find the real origin).

Given that it's been around so long, I'd be surprise if Blizzard were the first to ever "officially" use the term as a way of saying "we aren't telling you the release date yet."