I know he depends from pup to pup etc, but at approximately what age can dogs hold themselves the whole night?

You've answered yourself really. They are all different. I've found that if you crate your pup overnight they generally keep themselves cleaner overnight then letting them be loose.
I've done it both ways. My bitch was crated overnight. I'd get up in the middle of the night to let her out but at 10 weeks she was fine. My boy was a different matter. I tried him loose and he went everywhere even when I let him out regularly. I went back to crating and again he kept it clean and very quickly stayed clean all night.
For both of them I was up at six to let them out and their last trip to the garden was usually at 11-12 o clock.