Ask yourself, what three consecutive months of the year are we LEAST likely to travel? If it's July, August & September, go with an October use year. If it's September, October & November, go with December.
In other words (assuming those are the only two choices you have), If you think you'd ever like to travel in the fall, go with October. If you thik you are more likely to want a summer vacation in the future, go with December.
FWIW, if you really wanted a different use year and told your guide you wouldn't purchase unless you received that use year, (and really meant it) I suspect the use year points you wanted would become available.
