A very nice article appeared on Eurogamer about the start of wow.
World of Warcraft first popped into public view in September, 2001. Blizzard executive Bill Roper had flown into London to make an announcement at the ECTS trade show. Anticipation was high. The already legendary studio had revealed its (as yet unreleased) strategy game Warcraft III at ECTS two years previously, and the announcement of a new Blizzard game was a big deal. Even then, the studio was known for doing few games, very slowly – and very, very well. The smart money was on a sequel to its other strategy hit, StarCraft.