you should push this before christmas, probably the monday before, and here is why.
A) Alot of people take alot of time off during the holidays as well as all the schools are let out and there isn't much to do, so gamers will game. 2 weeks of pure testing and i promise most people will be interested in this update enough to get a REALLY good test into the system, even if it is on the PTS for a month or 2 before heading to live this is a big one and needs alot of testing
My work shuts down for 9 days during christmas, from the 23rd til the 2nd, and its all paid time off therefore again i will have 9 days of nothing to do and really want to test this content. As usual you have TSR looking to test the crap out of this update and help as many out as need to understand these changes.
and C) the last 2 updates were not tested completely and not given enough time on the PTS to get a good test in and get the new stuff up and running properly. Putting this on PTS during this time will completely negate this assuming that there is a team available during the time to fix the bugs and all that good stuff.
All that being said I understand ZOS probably has alot of people wanting to take time off to visit their families for christmas, but we really wont need alot, put it on PTS and let the bug reports stack up for a week or 2, and by the time they come back there will be enough work to get the new year to a good start.