You don’t have to wait until your son grows up to converse with him. True, he may not talk back, but he can hear and even see your lips moving at an early age. Talk to him, anyway. Show him his plushie puppy and speak to him about what is a puppy, what is a dog, what dogs do, how to groom the dog, and anything about dogs.
Include vocabulary words about the puppy’s world, like food, water, chew, toy, tail, nails, mouth, etc. Even little babies seek out stimulation within their worlds. Their mission is to grow, learn, and mature. Parents engaging their kids by talking to them and showing them how to do things is one of the best ways they can support that mission of learning, even if they can’t speak back yet.