4 months is a great age for a new pup. By that time, they can "hold it" a bit better than a younger dog. I got Jake at 2 months and he had to pee every 30 minutes on the dot and had to go at least twice during the night. He also had seperation anxiety from his fur mommy.

Addie was 3.5 months when I rescued her. She only had two accidents, ever, in the house. She usually slept through the night and was overall easier to train. Puppies are adorable, but after these two, I think my next new dog will be a bit older.