I don't know that you can count on codes being available. Don't base last year's code exodus on this year...last year was definitely not the norm. That being said, October begins another session of Regular Season rates, so you may see some discounts if Disney sees occupancy isn't where they want it to be. If they decide to do that, you *may* see codes in early summer - but that's just a guess on my part.
But don't count on it. If you book the GF hoping for a discount and it doesn'tpan out, you will be stuck with a bill you may not want or be able to pay. Book what you can afford and if you get a discount, be pleasantly surprised.