Well that is a bit of a dilemma. If you crate is just big enough for him to sleep in that’s step one. But seeing is u know he going to pee in thee crate it best to catch in on the act. When you do.. Shout out what ever command you use to scold him. Make sure it’s Loud.
not in his ear but it should be Really Loud and Unexpected. Personally i prefer to make certain sound to help my dog know he is doing something i disapprove of. The ideal is to distract in mid stream. When that happen rush him outside and wait there at his pee spot for a good five mins even if he doesn’t pee but if he dose really praise him. Also keep in mind that 12 week is rather young to have that potty thing down pack is bladder is a bit of a mystery for him as well as you an if you look hard enough at the forms you will see that there plenty of dog owners well into 7 years still having pee issues. I hope this helps