Supervision is Everything
Supervision is going to be important for several months, but it's most important in the first 24 hours. This is when your puppy might crawl into a closet or under a piece of furniture to hide; especially if he becomes overwhelmed. He may also hide to take a nap. If he does hide, it will be tough to find him as he won't respond when you call him and he doesn't know his name yet. Watch him carefully and, if you can't, put him in his crate while you're busy.
Supervising him in the house also allows you to begin teaching him the house rules. This begins immediately because you don't want him to learn bad habits. So interrupt him should he begin chewing on shoes or tugging on the drapes, and then show him where his toys are and teach him that these toys are fun. Praise him when he plays with his toys.
He's going to need to be watched him outside as well. A young puppy is helpless outside and he could easily get into trouble. Plus, hawks, owls, and coyotes can hunt puppies. In addition, when you take him outside you can teach him where in the yard you wish him to relieve himself.