Mine is a "get ready to settle down for a good sleep" basket. DD has always known that Mom makes it, we don't have Elves running around this house. (You could, but still have this as a "Mom" thing).
So there's both the timing of it, and the contents.
Contents:
In a cardboard box with seasonal decoration (it normally holds the Christmas books and DVD collection for storage year round, until they appear in early December to use until early January):
DD's stocking
DD's plastic plate and glass with Santa on them (toddler ones)
DD's hot water bottle with snowman cover
Family copy of "Twas the Night before Christmas"
New PJs for DH, DD and I
Sometimes some new slippers, fluffy socks etc to go with those
Lush festive bath bomb for DD (and relaxing one for me)
Sometimes, a nice seasonal but manly shower gel for DH
Nice hot chocolate for us all, and a Christmas craft beer for DH
We have dinner, which is a lot of different nice things, mostly cold, laid out on the table for people to serve themselves. Cooked and cured meats, prawns and squid rings, smoked salmon, olives, carrot and pepper sticks, cherry tomatoes, hummus or other dips, cheese, nice crusty bread or good crackers etc.
Then we go into the sitting room and (per Irish tradition), the youngest in the household lights the Christmas Candle - a red candle that should sit in the window to show any weary travellers that there is room in our Inn should they need it. (Youngest got significant help lighting and guiding the match until she was about 10!!). We then take a few minutes, as a family, to think about, remember and reflect on the good and bad things of the year just finishing, wider family, and to remember family members and friends who have passed away, finishing with a short prayer. (Not a particularly religious household, but it is nice to reflect on these at this time of year).
Then the box comes out. DD takes the plate and glass to the kitchen, to put on cookies she made in the afternoon (from scratch some years, but many years just slicing and baking from a half batch I freeze when baking earlier in the month, just in case!) and pour a glass of milk, and find a carrot.
She lays these out with her stocking. Then heads upstairs for her nice festive bath.
Into fresh new PJs, and down for the hot chocolate snuggled on the couch. Before I bring her up and tuck her up with her HWB, and read the book to her.
DH used to do many many bedtimes too, but Christmas Eve has always been a Mammy one. And we read the book every single year (by DD's request) until the Christmas just gone, where DD wanted to read it to herself in bed (now 14).
I know many others have theirs as activity baskets for earlier in the day, but we always had enough going on. DD would make her cookies while DH and I were also in the kitchen prepping veg etc for roast turkey next day. And new pjs are always useful in wintertime, so getting them on 24th has made sense to us to get snuggly and cosy in bed that night and make going to sleep more appealing.