It really depends on what time his last call for potty is. I would say two hours before bed time is a good time to cut off water. As a puppy though, Rocky probably won't make it through the night. The general rule is that a pup can hold it for their age in months plus 1. So Rocky in theory, can hold it for 3 hours at a time. With Jersey we would get up once, sometimes twice, during the course of the night. That lasted until she was about 6-7 months old. Even now, she sometimes wakes up in the middle of the night to go out.