Google is your friend in situations like this. I see a pretty thorough PokerNews article about the December Wynn schedule from 8/31/23.
https://www.pokernews.com/news/2023/...ntee-44383.htm
If we assume a similar timeline for this year, you'd expect detailed dates by the end of next month.
I've been tracking Wynn for August Signature Series dates and haven't seen anything for that yet, much less their December dates. IMO these venues could do a better job of giving us advance notice so we can book ahead, but it is what it is. They are going to draw a lot of players regardless. Right now they are busy finishing up the summer.
They've given us preliminary dates of 12/3-12/23 for the series. Based on last year's timeline, I would estimate roughly 12/7 weekend for the Prime starting flights this year and 12/14 weekend for the $10k starting flights. Those are likely to bleed into the following weeks.
Would not expect any concrete dates from Venetian, RW, or MGM quite yet. Venetian haven't even announced August dates yet. With the summer series and the imminent move to a new room, they may just be buried in other priorities at the moment.
Personally, I'm planning 12/17-12/23 for a December trip because the dates are cheap. I'll arrive too late for the marquee Wynn stuff, but hopefully they'll have a multi-day $1.6k or something similar on the tail of their series again like last year. Last year I fired the Prime, which was fun, but also a circus.