It was the first time I had to help one say goodbye. I hate when people say you will know when it's time. Sometimes you just truly don't know, it's very hard.
Dogs rarely "snap" without warning, same with most of these shooters. The warnings are just ignored, and I don't know why.
My condolences on your loss.
I'm no friend of the breed since I worked in an emergency room in EMT training almost 40 years ago. A 2 year old came in screaming. Pit had mauled the kid's face. With me and an orderly trying to hold him still with the aid of a papoose board, the doctor doing the stitching was still hitting a moving, screaming target. Kinda colors my perception still, 40 yrs later.
That said, I've known some very people friendly pits. My youngest has a rescue who will beat you to death with her club of a tail. She's a big sweetie. But if they have children one day, I'll still recommend they not leave the child alone with the dog.