You can bill her for your time to go there. You can bill her for the extra day. You can post a notice to vacate immediately..or face eviction filing (which you cannot do until the 2nd .. holiday and all that).
I would not trust that she is actually going to be out when she says. She has known since she moved in when the move out was expected to be... now she cannot do it then?
I never do a move out walk thru with the tenant. I've had such nasty scenes happen..I'll never get myself in such a situation again.