I give veggies and fruit to all of my dogs and puppies about 3 to 4 times a week. Carrots, cauliflower, broccoli, and apples make wonderful treats. I start teaching my puppies to eat veggies right from the time they start cutting their teeth. The hard veggies also serve as a wonderful chew, much safer than rawhide. When your puppy reaches 6 months of age, you can change him over to an adult dog food as most of your puppy's growth is now reached.
Many terriers have a tendency towards food allergies.
Make sure to check the ingredients on your doggy treats, the further away you stay from corn, wheat and soy products, the happier and healthier your dog will be. Do not feed a soft food or only canned food. If you do, you will have a dog with bad teeth, bad gums, and bad breath. Although your puppy has been wormed, I suggest you take a sample of his stool to your vet on your first vet visit. Your puppy has had at least its first vaccine as well.