Buzzy is 9 and will hold it 24 hours if he has too (which he had to about 5 years ago when I had the flu and was unconcious the whole time). Even now he holds it from about 10 pm (their last out of the night) until he feels like going out. This morning it was 10 am.
Last night Oscar (7 months) went out at 10 pm (their usual last out of the night), and I woke him up at 7:30 to go. He came up and went right back to bed with Buzzy until later though. There are some mornings when he will wake me up at 6 or 6:30 to go (usually weekend mornings
). He isn't exactly consistent yet but I feel like we are getting there.