The current stuff keeps the current reset day of Monday. Only some of the new content gets a reset day of Tuesday. I.e. so the servers don't get spammed with everything all on one day.

It says this quite clearly in the notes:

The challenge log has been added.
The challenge log contains a list of adventuring objectives across a wide range of categories. Completing any one of these objectives will earn you rewards. Completion status is reset on a weekly basis on Tuesday at 8:00 (GMT), and it is possible to undertake the challenges repeatedly. Additional rewards can be earned for overall completion of the challenge log.
* The time remaining until the challenge log is next reset can viewed under Timers in the Duty menu.
In order to alleviate server load during the weekly reset for item acquisition and player progress, the reset time for the following items and duties has been changed to Tuesday at 08:00 (GMT):
Allagan tomestones of soldiery
The Second Coil of Bahamut
The quest "Primal Focus"
PvP Weekly Performance
This is the only content that is getting the Tuesday reset time. Everything else is the same.