Small traditions that survive the exhausting years and still mean something when they are ten.

Sweeter than sugar cookies, this topic. I have watched families start traditions for forty years and I can tell you exactly which ones last.
It is never the elaborate ones. It is the small ones that survived a year when everybody was exhausted.
Before starting anything, ask one question: could I do this in a year when I have had four hours of sleep?
If the answer is no, it will not survive to become a tradition. It will be a lovely thing you did once and then quietly stopped, and the stopping will make you feel worse than never starting.
Choose small. You can always add.
Some things are lovely at one and become properly meaningful at eight.
Anything requiring nightly effort. Anything expensive that has to be repeated. Anything that only works if the child behaves in a particular way.
And be careful with anything that scales. A tradition where the effort grows every year will collapse eventually, usually in a year you least needed the extra guilt.
Your baby will not remember their first Christmas. You will, in extraordinary detail, so do it for you. Take the photograph. Buy the ornament. Do not worry that they slept through the entire day, because most of them do.
The tradition families tell me they wish they had begun sooner is a yearly personalised message from Santa. Started at one or two, by the time the child is eight there is a collection, and the earliest ones become extraordinarily precious.
Start the collection this year with a personalised message.
Pick three things. Only three. Make them small enough to do while exhausted, and then do them every single year without fail.
In ten years those three ordinary things will be what your child means when they say Christmas. Recipe for success, that.