A tradition becomes easier to repeat when everyone knows roughly when it happens.
Avoid the most crowded nights
Christmas Eve and the final school week can already be packed. An earlier December weekend may give the tradition more room.
Tie it to a milestone
Try the first Saturday in December, the weekend after the tree goes up, or the first night of winter break.
Protect enough time
If your tradition includes The Tomte Cake, allow space for the story, baking, cooling, decorating, and reveal rather than squeezing it between two other commitments.
Keep the date flexible when life changes
The ritual matters more than the exact date. If travel or work changes one year, move the night instead of skipping the tradition.