I got a ressie last week for my trip next week but the reaction of the CM making the ressie made me think it's pretty tough to get. I had her check on breakfast on the outside chance there was a cancellation, and there were none. I asked about just having dessert after dinner hours so the kids could eat in the castle. She said "let me check on lunch" and the next thing I heard she was squealing into the phone "OOOOOOOOOH" and I said "did you find something" and she gushed "I got you Lunch 2:10pm on 8/27 oh you have NO IDEA how lucky you are. I'm booking people into NOVEMBER for this lunch, oh wow you are so lucky!!!!!" Of course I took the ressie.
So based on what she said, it's kind of hard but I was able to get a ressie for less than 20 days.