As soon as a puppy can walk properly, he will start to explore his surroundings. Also, the recommended age to take a puppy from its family is around 8 weeks old. By this time, they should start their vaccination scheme, so do take your pup to the vet, because the answer to the question “when can my puppy go outside?” is in close relation to a strong immune system. Check with the breeder that gave the puppy to you if he has any vaccines whatsoever. If not, you have to take him to the vet. He will tell you how many vaccines you have to do until it is safe to take your puppy outside.
Of course, the vet will mainly recommend keeping your puppy away from other dogs and cats that may not be vaccinated and can be carriers of dangerous viruses for your young dog. Meanwhile, you can take your puppy out in the yard, as long as you have the time to keep an eye on him. If the yard is closed, and other dogs can't enter, it is safe to let your puppy go outside, even if he hasn’t all the shots completed yet. You may want to begin potty training outside, because the vaccination scheme will end around the age of 3 months, and you probably don’t wish to wait that long to start house breaking your dog. So, if you are wondering “when can my puppy go outside?”, the answer would be at any age, as long as it is a safe place, where you are around, and he won’t get in contact with other dogs.
I met people rather frequently that believed a dog can be taken outside at any age. I know that it is very hard to resist not to take your pup out for a walk, but the risk is just too high. They can contact viruses that are highly dangerous, even causing death, if you are not paying enough attention. These risks will be gone when your puppy will have all the vaccines done. Puppies from toy breeds, like Yorkie Poo, Pomeranian, Cavalier King Charles Spaniel, are most vulnerable. There is a good reason when the vet recommended to keep the dog inside and protected. I know you want to show all your friend the adorable fur ball you just got, but you are putting him in danger. They are tiny and very fragile, not having enough power to fight with viruses, without the immunization vaccines.
I know that my first question to the vet was “when can my puppy go outside?”. I am lucky to have a vet that explained everything to me, like the dangers of parvo and other life-threatening diseases that can affect young dogs. So don’t take this matter lightly. Still, I did take my puppy out even if the vaccination scheme was not over, out of the desire to house break him as soon as possible. I always made sure there are no dogs around, and never left him get near another dog. Also, I had a constant eye on the dog to make sure he won’t eat anything off the ground. The outside visits were usually short because I didn’t want to expose the puppy too much. But, in case you have a fenced yard, things should be easier. Still, don’t leave the puppy out on his own, not even in these cases. They are very fragile, and anything can happen. At least until all the vaccines are done, it’s worth having an extra eye for your puppy.