Maintenance for the week of December 23:
• NA megaservers for maintenance – December 23, 4:00AM EST (9:00 UTC) - 9:00AM EST (14:00 UTC)
• EU megaservers for maintenance – December 23, 9:00 UTC (4:00AM EST) - 14:00 UTC (9:00AM EST)
I think that's a safe assumption. So far, that's been roughly the timeframe of the other platform server updates and especially seeing this is only happening for XBox NA tomorrow rather than everyone or even just both NA and EU for your platform.
PS5 NA. GM of The PTK's - a free trading guild (CP 500+). Also a werewolf, bites are free when they're available. PSN = DragonRacer13