No, only big changes which are announced separately go live at a specific time after the update is forced.
Smaller changes and fixes are live as fast as you update.
So everyone updating before myth Titan ends can do all their attacks without lag.
People who already made their attacks before they update or who don’t get the update at all before the Titan ends will play with the lag.
Edit:
This one (epic golden emblems) is the only thing that will be available for all at the same time, the rest works when you make the update.