Great question - I've been looking at hotels for end of Feb 2015, and already they're filling up. Trying to figure out when to book - seems early, but...
I would check the hotel's actual site if you are using a third party site. I know I looked on Expedia and it said some were full but if you look at the actual hotel's websites some only have rooms up until the end of the year. So that *might* be the case with some of the hotels.. depending on the website you are using! Just a thought!