Wow, based on the responses here I am surprised so many kids can get up and go potty without waking up. That would never happen with my son. I guess every child is different, but I never had to wake him to go potty during the night.
Does your son go on his own when he wakes up in the morning? Does he consistently stay dry at night? I found that there really was no need to go through a separate process for night time training if both of these things are happening. I would say, if he is waking up dry and going to the potty on his own, then just bite the bullet and let him go without a diaper and see what happens. Just make sure no liquids an hour before bed, and make sure he goes potty right before bedtime.
My son is 3yo, and was potty trained about two months before his third birthday. He was consistently waking up dry and insisted he was potty trained, so we ditched the diapers altogether, even at night. He did have one nighttime accident about three weeks after that, but that was the only one, and it has been five months. He just goes before bed, and when he gets up in the morning, like anyone else would do. Some kids might have smaller bladders, so I think that waking up dry is your best indication that you can eliminate diapers at night. But that can be tricky, because how do you know he didn’t go in his diaper right AFTER he woke up just because it was convenient? Like I said, I think the only way to know for sure is to try without and see what happens.