I'm a retriever trainer. Leatherwood Gundogs is my kennel. You can and should absolutely start training obedience and crate training now. Depending on what you want the dog to do as an adult you can start basics of whatever that is now. Remeber to keep things light and fun. Stay calm and don't lose your temper. Remeber that a dog can't reason so if you come home and he has crapped in the floor there's no need for heavy handed reprimands. The dog will just lose trust in you and think "Man, this guy is a ticking time bomb." I'll answer any specific question you have anytime you want to pm me. Some good books to pick up are "Leader of the Pack", anything by Mike Lardy, and "Speed Train you own Retriever". Let me know if I can help with anything.
Love this and from a gun dog trainer!
The only worse advice than marriage advice on the internet is probably dog training advice.

There are just so many perspectives, methods and opinions and people lose their shit if they disagree with you. I became infatuated with dog training over the last 6+ years and unfortunately (if you want to call it that) it is because of raising a dog that is scared of the world and would fail damn near every facet of the temperament tests except for his loving all people.
Coming at this from a companion dog perspective:
1. SOCIALIZE that puppy to everything you can possibly think of. All kinds of people, all kinds of dogs, all kinds of places, noises, smells, EVERYTHING.
2. Google "crate training a puppy" and read those differing articles until you're tired of it. The short version: introduce the dog to it slowly, with the door open, letting him go in and out. Let him have his blankets, some toys in there, etc. Get him going in and out of it and enjoying spending time in there. Let him fall asleep in there for naps and slowly start to work on closing the door for a bit and going from there. Then you can start working on "kennel" or "house" and rewarding him for going in and out.
3. Start training him yesterday. You can teach the fundamentals to sit to a puppy in minutes and he will be happy to do it for a piece of kibble most likely. Puppies especially are often more than happy to work for their regular kibble. I would do some basic obedience type stuff with half his rations, then let him eat the other half or so. If you feed twice per day this gives you two training opportunities every day. Do a little here and there instead of an hour later.
4. You should be giving a puppy a lot more opportunities for reward than correction. He will figure that stuff out as he knows and learns commands.
I never feel like I can put enough info out there in a single post and there are people far more qualified than me. I can tell you in the last several years I've seen and worked with everything from "If the (adult) dog is biting you, just reward him when he is not biting you" to IPO/protection sport people cranking their dogs for swinging their ass too wide in heel. Like all things in life, I think some middle ground is probably the right answer. With that puppy though, remember this: He doesn't know anything. Everything you want him to learn you need to show him. And you didn't learn anything the first time. Make him your best friend, trust you and you'll have a lot of great years together.