Welcome to YT!! Give yourself credit for several things right off the bat - you have a good vet, you found YT
& you are preparing yourself with supplies.
It sounds like Brady will identify you as his momma. Are the plans still for him to go back & forth between houses in a few weeks? Will someone be available at the other house to actively interact with him & help with housebreaking. I think housebreaking can be difficult enough without figuring out where he's suppose to go if he is pad trained at each house.
I hate to say this - gosh, we don't know each other, but at 16, what happens to Brady if your son & gf break up? That is a lot of pressure on them & on you, as it sounds like your already attached to Brady.
Keep reading her on YT & ask lots of questions, that's why were here - and to share a few laughs