I don't know what marks the beginning of the Christmas holidays for you but for me it's when my Thanksgiving cactus (Schlumbergera truncata) starts to bloom. Not exactly the best of signs because some of my plants bloom as early as September!
The leaf cactus I have are a collection of plant gifts and after Christmas sales plants. Since their identification tags were missing, I plopped them into hanging baskets in a basement window with filtered southeastern exposure. The basement stays cool all year around; they prefer temperatures around 65F, although plants in my office were exposed to temperature fluctuations and still bloomed well.
My main challenge is not to over-water. These are leaf cactus, after all, requiring less water than most and more than some.
Besides cooler temperature, the other requirement these easy to grow plants have is light exposure. To prompt them to bloom, they need a period of less light. As the seasons change and fall daylight gets less, that change in light exposure is enough to tell the plant it's time to bud and bloom.
And how do I know this is a Thanksgiving cactus instead of a Christmas cactus?
Unless you have a very old plant, most plants sold on the market today are Thanksgiving cactus, grown to bloom around Christmas for gift-giving.