Way, way back, I started scheduling Christmas music on Thanksgiving day. For those outside the USA, that always falls on the 3rd Thursday of November; about five days before the big day. After that holiday weekend, I'd schedule one Christmas song an hour for the next week. Two an hour the week after. Three an hour the next and during Christmas week, I'd schedule four an hour. Strange as it may now seem, that was really rather radical. My first decade or more as a DJ and PD, the standard action was to not play much at all until Christmas week. And on the 26th of December, everybody dropped the seasonal music altogether. Seems strangely half-wit now in this age where every market has at least one station that goes all-Christmas each year, I know. And, actually, because of that in some markets I've advised easing up on the Christmas content, maxing out at three an hour for the final week. This is all a judgment call for the PD to make and depending on format, you might not want to play any at all. Like, how many Hard-Rock/Heavy-Metal Christmas songs are there, right? FYI, here is an older article I wrote and distributed each year to the stations I was consulting. I updated it a bit a couple years ago. This one is all about the Country format, as that's what I've worked in exclusively for many years. The techniques were born and first used by me when working in the CHR and A/C formats, so it's relevant still. Just the song titles and artists are different. That link gets you a pdf file.
Below is a link to another page on the blog here with some videos about how to get it done. These vids were made some years ago and are a bit fuzzy, but there's now change in how it's done, so pardon the look of these.