W.S.
I didn't move my son until he was about 3 1/2. I had to put rails on both sides of his bed, but he did fairly well. Whenever you decide to try, you could transition from crib to bed by removing the bed from the frame and letting him sleep on the mattress on the floor. He might consider it an incentive to sleep there rather than the more restrictive crib. Then when he is sleeping well that way, either just raise the bed, maybe on a special occasion such as birthday or holiday. Just a thought.