Well, going by this quarter (Oct-Dec) - cars were built from early October to around 1-2 November. I think the first ship arrived in the second week of November, and I don't know if anyone got a delivery before mid-November? There are still folks waiting for deliveries with estimates up to end of December.
I've only been obsessively reading the forums since I ordered on 8 November (too late for this quarter, was already 8-12 week estimate then), but as far as I am aware the same schedule has been the case for the last few quarters at least. TBH they really should just say "Early 2022" until the car is built.
Also at the start of Feb next year is Chinese New Year where everything shuts down for a week as people go back to their families, if your car isn't on a ship before then that'll likely affect things as well.
I hope you're right, I'd love to get my car in Jan, but unless something changes and it gets built in December I don't see that logistically being possible.