What a lovely thread!
My childhood Christmases were in the 70s & 80s. It was only ever mum, dad, me and after 8 years, my sister as we lived in N. Ireland and the rest of the family were in Scotland and England. But many of my parents' friends were in similar positions, so there were a lot of parties to go to in recompense.
Decorations went up on the last day of school. I vividly remember the old black and red Woolies box mum kept her beautiful glass baubles in. Although we had a real tree when I was a preschooler, after we got a cat mum bought a white artificial tree which we used until dropless trees were developed. The white tree and coloured fairylights are just Christmas to me even 'though my own tree and lights are so different!
We would often make paperchains or Blue Peter style advent crowns (without the candles!). I remeber a brillant castle mum once made out of card which we copied from Blue Peter and she put the sweetie stash inside it.
There was a fire in the hearth every day, and the rest of the house often being freezing because mum wouldn't put on the central heating during the day so you would dash to the loo and back! I remember lying on the hearth rug playing (often with my kid sister's toys, the Fisher Price camper van was a particular favourite) while mum and dad read or watched the telly. On Christmas day my sister and I opened stockings together, alternating beds annually, other presents were after breakfast.
For many years the dining table would be covered with dad's old OO model railway which I loved and we'd eat Christmas dinner off our knees but I got a bit houseproud around 10 and started insisting we eat at a table, and at that point started taking control of laying the table (obv. poncetastic tendencies early on). We always had Christmas dinner on Christmas Eve in the evening, with a repeat on Christmas Day in the evening, after a massive cheese and pate board during the day. After slobbing for the day, we would always change for dinner.
And the Radio Times and TV Times (the only time of the year my mum bought the latter), bought as soon as it came out and then we would each go through and mark what we wanted to watch. Mum would then hand-drawn a spreadheet/gant chart thing of what was on when, noting any clashes, which she would stick on the back of the living room door.
It was one of the few times of the year dad would spend extended time at home, not interrupted by work or student football or that in itself made it special.