If you’re still actively submitting queries and submissions my suggestion is stop. In fact, stop by Thanksgiving. It’s exactly what most agents have done when it comes to submitting.
Let’s face it, publishing isn’t that much different from many other companies. People are busy with holiday parties, shopping and daydreaming about sugar plums (whatever those are). Getting to submissions at the end of the year is either bottom of the priority list or falls somewhere between clean off the desk for the new year and regift the fruitcake. In other words, you don’t want to be part of the office cleanup.
So hold off, polish your letter and your manuscript, take some time out to enjoy a festivity (or holiday cocktail) or two and be ready to hit the ground running come January. Maybe January 15 so you give agents some time to clean out everything that’s come in while they were busy eating the figgy pudding.