If your cat is used to sleeping with you, you may have to use the bathroom. If circumstances permit, do this at least two weeks before bringing the newcomer home. The isolation area should be cat proofed and well ventilated. The simple set up should include a litter box, a water bowl and a cave like hiding box lined with something comfortable. The visual impression made is important.
Cats go through the same developmental stages that people do.
He has no life experience to guide him in his decisions. He will make tactical errors. You must be there to help him cope. A juvenile is a kitten between 12 weeks and 6 months of age. Full of energy and enthusiasm, he can be a downright annoying companion.