With family scattered across the country and internationally, it requires decisions early on about who is traveling. As both families live close together and have others to stay, the chaos is too much, so if we travel for Christmas, our nuclear family books a cottage locally (very few available) so need to do that before April. (As DD has ASD, we really need that space to retreat at times).
If we want to do any Santa train, that needs to be booked in August - it’s great, but the only one is very popular. We only managed it 2 years.
Dh and I both work FT and stressful jobs, both have international travel, and have to juggle DDs sports and seasonal activities, my Cub packs’ Christmas events and other seasonal events at work etc. and with no family local to us, we need to get in early with the 2 teens who babysit to book their services.
I also need to book online food shopping slots as everything gets so manic.
And as I have over 50 people to buy for, and DDs birthday over Christmas as well, I neeed to get started early on that. As well as on various crafts I do some years as presents.
And in our house, Christmas is a season - there’s advent all through December, and the 2 weeks that dd is off school (we usually take a lot of that off) and we need to visit family over that time whether on the day or other days - juggling all the various diaries and trying to not get anyone too annoyed (we never ever spend enough time with either side, they both always feel we spend too long with the other - and we actually need to build in quiet time for ourselves too).
So yes, doing that earlier in the year than 2 weeks before is vital!