Actually, you are late in starting grooming!
The best time to start grooming is the day that you bring them home.
You want to get them used to being handled, both my yourself and by others.
And puppy nails still need trimming every few weeks.
So start by handling the paws and ears Holding pup in your lap, stroke and gently pull and squeeze the paws and ears. If pup stays quite, treat and praise. Puppy nails can be cut with people nail clippers.
Do the same with brushing. Gentle to start....just to get him used to the feeling.
Then you work your way up, up, up. You are trying to build their confidence here as early as possible so that it becomes ingrained into their behaviour.
But one cautiuon.....if you need the nail quick even once, you'll find yourself having to start again. These pups have long memories.