Here are the finalized weekly update times which are already in effect:

Massacre: Every Friday, 21:00 Game time
Standard: Every Friday, 21:00 Game time
X-TREME: Every Saturday, 21:00 Game time
Speed: Every Sunday, 21:00 Game time

They are also mentioned in the weekly stats pages of every universe.

Notice: all updates moved 1 hour earlier. Post above and game pages updated to show the new (correct) time.