It's too early for discounts for us December travelers - although I am anxiously awaiting them too! I think the earliest we may see something for our timeframe will be the first or second week of June. Why? Here's my theory:
The spring discounts (April, May and first part of June) were available to book until March 17. We then waiting until April 1 for the summer (6/23-8/24) rates to be available to book. These summer rates you can book until May 19. So far, Disney has left a 2-3 week gap between discount code releases.
So, if we are lucky, Disney may decide to release the next set of discounts for the rest of the year in June. It's hard to tell since they seem to be releasing discounts in 2 month blocks. If the pattern holds we may see discounts for September and October in June and bookable through mid-late July. Then after a 2-3 week gap, we may see discounts for November and early December (or all of December, you never know) bookable in August.
But this is all idle speculation. It's too bad they just won't reward us advance planners and just give us the discounts right now. It would save us all a little time and Disney would still get our money.