I would wait and see. It might only confuse him.
If he can hold it for 9 1/2 hrs I wouldn't worry. There are times
that Bud and I sleep from 10:00pm until 8
o am. I get dressed
and take him out. That's 10hrs with no problem. Bud is younger
but I don't think that matters much, if there are no bladder problems.
I would give it a try first before changing things in his life. It
will totally confuse him. Like they say if it ain't broke don't fix it.