If you are refering to the one in Epcot (as opposed to CRT), remember that the PS can be made 120 days in advance! However, I had no problems calling about 75 days out. I was told that they really start filling up at 60 days because if someone cannot get CRT they immediately request PS for the Princess bfast in Norway. This bfast is pretty new and I don't know what the possibility of a "walk-in" would be. I've heard of people getting lucky at CRT for same day, so why not at Norway? I don't want to jinks myself but we've never had a problem getting a PS for Cindy's or anything else, maybe because we always go in November?
Just keep trying, you never know what might open up!