Just a suggestion - If this is done at 4:00 pm Tokyo time on a Monday, 90-95%* of the player community will not be significantly affected.
This translates to:
7:00 am GMT
2:00 am ET
11:00 PM PT
War: For most players, war will not have started yet
Rewards: For most players, it will be outside the 2-hr claim period for stamina
FP/Coli: For most players, it will be outside fp/coli rush hour...
I have no stats to back this up but I'd also suspect that server load is probably at it's lowest during this time frame with folks getting back to work and/or sleeping.