As you said the GCV's is the smallest DVC so it can be hard to get. I had good luck at the 7 month mark but I was online 15 minutes before online booking began, and had my computer all queu'd up and ready to press book the minute the clock hit 8am EST.
Sounds like you have some flexibility in your dates so that is always good... and studios are much harder to get, so if you can be flexible and take a 1 bedroom that is good too.