New dog owners overnight

My partner (24) and I (25) went over to his sisters last night to check out their dog that the family has been wanting us to take. We were looking at getting a pup anyways and it sounded like a good idea.

The dog is a pitbull maybe mixed, bought from someone off the streets, not neutered, and younger than a year. I have a lot of experience with dogs in and out of my life, however I’ve never had to train extensively….The conditions of the house were tough since they lived in a small apartment with a 3rd kid on the way so we decided that night to take him. He’s a little more skittish than i like, but so sweet and playful in a safe way. I just don’t want to feel like this is the biggest mistake ever, i’m looking into training but besides training, getting neutered, and completely adjusting our lifestyle how can i make this transition feel better?

I’ve wanted a dog since my last one past but we jumped into an intense breed pretty fast.