Letting a rescue cat out

[CaptMorgan]

We've just adopted a cat and the rescue said to keep him in for 8 weeks.
We've had to open the windows a little over the last couple of days but we caught him trying to climb out last night!
We tried a lead in the garden but he just doesn't like it at all.
We've had him for a fortnight and he's very domesticated, he's definitely been with a family before and he comes when you call and shake the treats! We've been shaking the box of biscuits when we feed him to associate the noise with being fed too.
How long would you keep him in for?

Another couple of weeks probably. Then make sure it's just before feed time!

We kept ours in for 3 weeks. He seemed fine but doesn't venture further than the end of the drive.

The rescue told us 3 weeks. If yours said 8 could it be specific to your cat's personality or history?