My usual time for Candolim is November-December, and I've always loved going just before Christmas, getting some hot sunshine, a lovely tan and lots of presents before going back for the party season. It's usually pretty quiet at this time of year and the beach is nice & clear.
I have to admit to being slightly apprehensive about actually being there for Christmas itself. Is it going to be a huge shock for me with hoards of people everywhere? Will the beach, shacks and restaurants be packed and hard to find beds/tables? Are there going to be hundreds of kids screaming about the place?