Team bonus - training

Managers friends
The question I would like to solve is about training. I know that every day the team bonus drops 2%, but I would like to know exactly what time that 2% drops, that is, what time one day ends and the other begins.
From my experience in other games, I think it has to do with the time zone of the city where the central game server is located. It is worth mentioning that I am from Mexico.
Have a good day.

It should be during the daily maintenance, around 3.15am GMT. So that would be 9.15pm or thereabouts in Mexico. You are 6hrs behind the UK.