I have no idea this year.
We are putting up the fake, as we are travelling over Christmas itself, so timing is therefore immaterial.
However, as DH's Dad died earlier this month, and MIL will be visiting us just after the month's mind the 1st weekend of Dec, I don't think I want it up before she comes. DH is not as festive as normal (he is slightly the Scrooge to my Christmas mania but has improved over the years to actually planning stuff with me now!!). But at the same time, I am not sure yet quite how festive he wants to be - although he did say that while he doesn't think his DM will send cards, he doesn't see why "we" (read that as I - the normal scribe of all cards in the Pop household!) shouldn't be sending them as normal. We normally get cards supporting charities anyway, so it would be supporting a specific charity this year.
I may see if DMIL is up to putting it up while she is with us - probably staying for a week-10 days. All activities finish up (well, Saturday ones at least) on 5th, so the 12th could be good. Or else, some evening the following week when DMIL is gone home.
I will scale back the decorations in any event. Not so many window clings, garlands, and snowglobes as normal. And probably bring out the big nativity instead of just the small one we've been using in recent years. A bit more of the tasteful and understated style this year, rather than the glitter fest of recent years.
I MIGHT actually manage to make the advent wreath this year (I have the candles and have been threatening this for at least the past 5 years!). And I will put out the Advent Calendar on 1st December. And DD will put her favourite snowglobe in her room then as well, and her fleece blanket with a Santa scene on it will find its way into the sitting room too. But otherwise, I suspect, later and more toned down than usual.