I made Proxima the Human Hunter when Cataclysm dropped, he stopped at 35 and had been sitting in Duskwood. I slapped some Heirlooms on him, discovered the Darkmoon Fair buff and set about levelling. the old world I wasn't surprised about, but entering Outland at 60... wow. Trollbanes Command + Darkmoon Fair + heirlooms = i was level 65 before leaving Hellfire Penninsula. Only quests, no dungeon finder.
I think it took me a month or two to hit 70 in Outland when BC released.