Quoting MommyingWithGrace:" My oldest was 4 when he was fully potty trained and so was my stepson. I guess I was kind of hoping that my son was a late potty trainer because I didnt know what I was doing. "
I feel like most kids will PT when they decide they are ready. But there are other things you could do to push it along. Do you have a potty seat in the room he's in the most? When you're at home have him naked from the waist down. As soon as he wakes up in the morning keep him on the potty until he goes. Make a HUGE deal when he does go, & also don't get super upset when he has an accident