For how long?

For how long? I'm going to assume you're referring to how long Jem must visit Mrs. Dubose?

Jem ends up fulfilling his punishment for the initial month, plus one week.

Atticus put out his hand and Jem was silent. On the way home, Jem said he had to do it just for a month and the month was up and it wasn’t fair. "Just one more week, son," said Atticus.