It is fine to wait until you are 100% sure. Colleges count on a certain percentage of accepted applicants turning down the offer of admission so it is not like the admission officer will run out and extend one more offer when they find your D turned them down.
FWIW early in the process my S turned down two EA/rolling schools that he was sure he would not attend (had offers from preferred schools at same or better price tag). However, he did hold onto a couple of other EA/rolling offers until the very end – we attended the colleges’ accepted student days in April. While ultimately he did not attend those schools, they were truly contenders.
So my advice is to do what makes sense – IMO you D should not give up any acceptance until she is very very sure that she will not attend that particular college.