I don't know how much you should give him. Shelby only has dry food and she eats about a fourth of a cup twice a day at 9 months. She is not much bigger than your little one. (she gets tiny pieces of treats, meat and veg. too)I make sure her food is available all day and at night if she hasn't finished it I put cooked vegetables on it and she gobbles it down. Occasionally I give her chicken on it but I don't want her becoming one of those dogs that wont eat dog food. she likes vegetables a lot!
If you have the energy
you might want to try to sway pup away from eating wet food. maybe I am repeating info you know (sorry) but this breed has teeth issues so dry food is a better choice. I know how hard changing is but it will be easier now than later. good luck.