There's a difference between morally "should" and legal obligations.
So while we all "should" give employers, service providers, tenants or anyone else plenty of notice of a change, whether we have to depends on the contracted terms.
Is it unprofessional for a day home to make a change with such little warning? Absolutely. Did they have to give you more notice? That totally depends on the contracts you signed. From a moral point of view, most day homes give notice of significant changes that are at least equal to the notice period a client would have to give, should they not agree to the changes. But if there isn't a contract, or if the contract says that changes will come into effect 7 days after notification to the changes, then that's what will happen.