You can find all of the dates for 2019 here.
Additional details regarding the January 1-day event will be posted soon.
There is no event in December, as the 7K staff will be taking a break to prepare for the next season. During this time, you can still purchase the December event to help support the game into the new year. For doing so you will receive four/five build, credit towards a 12/18 month gift, and another chance to learn stuff from your trained list of skills/spells/feats/etc. Furthermore, you will receive a second roll for glory in January. The December credit is available until Dec 31st. Thank you for your support.