Routine is everything to a young child. Talk to mom - tell her this. It is in her child's best interest to remain on routine. And they need to use YOUR routine because YOU are the one who has the most scheduled day out of necessity for the group.

BTW, this is why I have a three-day-minimum attendance requirement. It allows the child more time per week to get on YOUR schedule and you will find that the more days a child is in your care the more they will start to naturally mimic your schedule at home.