If he is eating the canned food now I think you'll be okay.
I've posted this before but when we got Ranger the breeder was feeding him Mighty Dog chicken and rice, she told us that he got sick eating anything else
. So that's what we fed him for about a week before I went and bought Science Diet Puppy chicken and rice. I added about two tablespoons to his Mighty Dog and he didn't even seem to notice, nor did he get sick. Over a week I had switched him to the Science Diet and he had no problems. After a month I bought Science Diet Puppy dry food and began adding that to his wet food. Slowly we weaned him off the canned food and a few weeks later he was eating the dry food by itself and wasn't being picky.
If he gets hungry he will eat, Ive noticed lately that Ranger doesn't eat as much as he used to. We give him breakfast and sometimes he wont eat it until its almost time for his dinner. At first I was scared but he eats all the food when he's hungry so that makes me feel better.
Good Luck with your pup!!