If you have marketing plans for the Christmas break, then now is to plan them.
You will want your offers, or marketing messages to be out there between 4 and 6 weeks from the 25th December. That means you only have a few weeks to make plans and start getting everything into place. A last minute email on Christmas Eve is going to be too late for anything.
How does your market react to this festival. Is it a time of boom or bust?
Who makes purchases at this time. Remember that most items are going to be presents, so it is not your target users that purchase, but the people near and dear to yoru target audience that purchase. So, you either need to nudge your targets with things they can pass on, or you need to attract the attention of the present purchasers directly.
There are no answers in this post becuase the subject is too varied for a genereal answer. That is why I raise the flag so early. You need to put on your thinking caps and cast your mind back to last year.