Many people here (me included) suggest a harness instead of a collar. Their necks are small and fragile especially at the age they come home to you!
Are you going to crate him at night?
I also suggest a few fleece blankets. When they're potty training sometimes they get pee on their underside after the fact (especially boys...) or they walk in it by accident, and then get it on their bed. A couple fleece blankets gives some options to be able to substitute out something soft to lay on while the bed is in the wash.
I had trouble finding baby sized fleece blankets, so I just got a cheap throw size, and it works ok.
Start with asking your breeder about what food he/she uses. Sometimes that's a good place to start. Even if you switch food, you'll need a small bag of whatever they use to be able to slowly mix it and change it out.
We put a scrap piece of linoleum under Trooper's expen so that if he does have an accident in there, it's easy to clean up.
Microfiber dog towel makes drying him a lot easier because they soak up a lot of water off of him.
Shampoo/Conditioner (I'd start with asking the breeder about this too, they've probably tried a million and know what works on the mom and dad.)
a cute tshirt.