I changed my hours a few years back. It was a total of 1/2 an hour earlier closing time.
I had 1 family who was here my full operating hours, and none of the other families needed that length of care, so when she went on maternity leave(the long day parent) I gave the families 2 months notice of the 1/2 hr earlier closure. I knew that none of my other families would be affected by the change, and no one complained. They had the option to leave, and none did.
For me it was a game-changer. That small difference in time allowed me to get dinner ready/kids activities in the evening/earlier bed time etc. Such a small thing, but huge to me. I have never looked back. On average, the business still requires 60-65 hrs a week, and takes a lot of time on evenings and weekends to keep running.
The lack of notice by the caregiver was unprofessional. I would think at least a month's notice would be courteous, as the hours changed at both opening and closing.
She may have felt that if the majority of families were not using those hours, then why not scale back the hours.