How do I handle a repeat client not abiding by boarding = 24 hours of care?

Not sure how to handle... I have a repeat client that I agreed to sit. Several days before the visit, when I contacted to touch base, she stated she needed a drop off time of 6:40 am (on a Saturday mind you), and a pick up of 9:30pm (which happens to be Halloween). I understand that I should have verified drop off and pick up times before agreeing to board, but it was a repeat client so I guess I didn't realize it would be a problem. I certainly don't want to lose her as a client, as she has three dogs who are great, but I'm feeling like my time is not being valued, let alone compensated.

I have asked her to bring the dogs the night before "since that's kind of early for a Saturday," and am not looking for additional money for this particular visit, as I feel that would be unprofessional. However, I would appreciate any advice on how to handle this so as not to have a repeat of this in the future. How do I handle this without losing her as a client?

Thanks in advance!