Since you use "visitation" in the context of sentences being cut for good behavior and serving time, I interpret this to mean visitation to someone in prison. When someone is serving a prision sentence for some crime, they may have the right to be visited by their family or friends. That is what it sounds like to me. But, the word "visitation" could be used in religious, social, or official contexts.

Visitation can also be a punishment from God, though sometimes it may also refer to some reward from God. It can also mean a visit from any supernatural being.

'Visitation' often refers to seeing a ghost.

What does mean "visitation" here?

Silas got a good chunk of his sentence cut for showin' such good behavior. - Don't tell them that. - But it's true! I'm not ashamed to tell them. - Camille... - Just shows how worldly you are. You served your time, and now you're mine. I would go see him during VISITATION.