SimGuruKate over at Twitter announced that the December update is set to release on Tuesday 18th of December 2018 for PC/MAC users!
Attention! The next patch (PC/Mac only), which will bring the fun holiday content shown in last week's Maxis Monthly, as well as some important bug fixes, is currently set to arrive next Tuesday, December 18th. Please remember this can change due to unforeseen circumstances.
— ❄️SnowGuruKate❄️ (@SimGuruKate) December 12, 2018
New holiday items are being added in this update along with bug fixes that the game has been facing since the latest update which was released for Get Famous. This is not an exact date and it may change but right now its set to release next Tuesday. If even changes we will let you know.