September is about right. They start making the 05 in Mid-July and by mid-September most dealers have a few. October is when you start seeing more & the 04 are on the way out.
As far as waiting, usually in September the newness hasn't worn off and they won't go down much, even if it isn't a new body style. If you are planning on getting a V8, I have read rumors of a slight increase in horse power. Rumors are usually 25% correct, no make that 2.5% being correct.
I was in the same situation in mid-2000, I looked at 4Runners and if I found a great 4Runner at a good price I would get it, if not I would wait. It turned out the deals were better in 2001. You are in a good position of not being under any pressure.