Keep him inside. If this is your puppy, if you chose him, if you paid for him, it's your decision. You may have to debate a little with your parents, but what is there to argue about, really? If your puppy sleeps indoors, he should be in a crate. If you all are working, he should be crated. And if you all work at the same time for extended hours, put him in day care or with a friend. Don't leave him outside, especially not at 3 months. Not only is he at risk of escaping, but he's also at risk of being stolen and being a cute puppy is not playing in his favor.

Also, if you need tips with the potty training, we're more than happy to help