Going through the same thing now! I just adopted a 12 week old pit puppy and have been slowly introducing him to my 1.5 year old female pit. The first couple of days were rough but they’re adjusting. Since both weren’t used to being around other dogs, each was pushing each other’s buttons. The puppy quickly learned where his boundaries were and after 1 incident with biting, they’ve been much more at ease with each other. In fact, yesterday the puppy was following the older one around the around and trying to steal her ball (which he learned very quickly he can’t do… now he just gives it back).
Don’t leave them unsupervised. If you notice your older pit getting too close or getting a look of agression in his eyes, tell him to back off. With just saying “No.. back away” my older pit knows to avoid the puppy and vice versa. Find a place where they both have plenty of room to themselves whether it’s a room or the yard. Spend equal time with each animal that space and make sure you praise them when you see god behavior!
Just be patient! Don’t stress if they get into a few tussels at first. Remember, they are both having to adjust!!!