Probably around 6-7 months Ralphie could hold it for 8.5 hours. I think that dog has bowels of iron, too, because if he wants, he could probably hold it 12+ no problem. Last winter we had a horrible cold spell, and Ralphie would not go outside. He might have gone in the morning before I left for work, but it was so quick I'm not certain. Held it a full 8.5 hour work day. It was windy and horrible still when we got home, still wouldn't go. He had plenty of opportunity, and at that point I wouldn't have cared if he went in the house, but he would not go potty. Before we went to bed and the wind died a bit he finally went out for what I imagine was the longest pee of his life.