The start of the Halloween event means absolutely nothing as for the timing of the patch. If the items were added in 2.38 then that means all they have to do is flip a switch to activate the event when it's meant to go live, it's been the same with every single other event they've had.
As I said before, we are not seeing this patch till November, too much rides on it to help them lessen the blow that WoD will cause with everyone going back to it. Wondering how so many people seem to think that we were somehow getting it in the middle of the month before fanfest, when no live letter had ever been announced before then. They are adding a new class in this patch, those things take time to balance and if that means "delaying"(saving a new class for a "special" occasion) the patch to make sure it's not broken beyond belief off the bat, then that's what they're going to do.