Call today and see what you can get....and then if you don't get exactly what you want, keep calling back. People cancel/change things every day....and honestly, I really think they hold back some tables or something. I can't tell you how many times I've read about how this or that place is booked solid for someone's entire vacation and then a few days later someone else writes that they got not only the restaurant but the typical dinner/lunch hour not some off time.
And, I can say that has happened to me quite often. We're going end Nov/beg Dec and people are talking about how impossible it is to get reservations, so I start to panic because my 180 days are long past but we're being rather slow in figuring out what we want to do, so I hadn't made many ADRs. So I call figuring I better just get SOMETHING so we aren't stuck with CS the whole stay. I get lunches at 11:30 and 12:30 I get dinners at 5 and 6 pm.....and one poster said she'd been trying to get 1900 Park Fare for the same week and nothing available anywhere, and I get breakfast at 9am one day and dinner at 6:30 another day. And we have the same party size, so that wasn't it either. I kinda felt guilty that I got it with so little effort, but hey, I didn't have any strings to pull so I guess I just got lucky.
Also....it is said that about 45 days out is another good time to call.....people are cancelling trips before the deadline and so their ADRs open up also.