The most important and colourful part of Ukrainian Christmas traditions is the actual Christmas Eve, or “Sviatay Vechir”, which revolves around the twelve course Lenten supper, This is a family affair or reunion commemorating our ancestors, and the religious observance of Christmas, it is acknowledged on January 6 th prior to Ukrainian Christmas Day by the Julian calendar, established by the Roman Emperor Julius Caesar in 45 BC.

https://www.ukrainianwinnipeg.ca/traditions-in-ukrainian-christmas/