My pup started going through the night at about 17 weeks - when he went to stay with my mum for a few days. It only lasted a week, though, and was then back to waking up early, around 5ish. He was back to all the way through a few weeks later, but then we went away and he woke in the night then a few times. About 6 weeks ago (at 23 weeks, he started sleeping through properly (past 8am some days), and we also decided after a few days of that to leave the crate door open - has been fine ever since. Sometimes I now wake him up (having woken up myself and worrying that there's no noise from him...)
Obviously all dogs are different. I'd give leaving him a go - see how he does. If it doesn't work out, then just see it through and remember that he will grow out of it eventually. Could you also try a different routine? Take him somewhere new?