Accepted students are in a different category than prospective students. If your child can’t visit during a special admitted students event and you need to schedule at another time, most schools should be accommodating. They want your child to attend! Tours for accepted students are unlikely to fill up in advance.
For my child, the most critical part of the visits after acceptance was the opportunity to sit in on a class or two.
We actually did plan in advance without having all acceptances in hand because air travel and driving was involved and the window of opportunity was very restricted because of a time-intensive EC. Had our child not been accepted to all schools on the visit list, we’d have substituted shopping and tourist attractions for campus visits.