I converted at 18 mos., but if he isn't climbing out yet then I would just leave him in the crib until he does. When he does start climbing, I would skip the toddler bed and go straight to the twin, it saves time and money, plus he will outgrow his toddler bed so quickly it's not even worth it. My son is 26 mos. and has just left his toddler and moved into a twin. He's doing great and stays in his bed, even for naps (most of the time). How we get my son to stay in is we have a scheduled routine that we stick to. Story on the couch and then hugs/kisses and then he knows that he has to stay in his bed. WE tell him to stay put. You have to be firm. If he keeps getting out, you just keep putting him back in until he stays. But do not stay in his room with him, not even once or you'll be doing it every night! Do not lay in his bed with him either, you'll be doing that every night too! Stay outside his door and if you hear him getting out, open the door quick before he has a chance to climb all the way out or before he gets to the door. Tell him, "GET IN BED!" It will make him feel like you know, even though you can't see and that you'll catch him even if you're not in view. Since I stay at home with my son all day, it is easier for my husband to actually put my son in his bed rather than me. My son tries to manipulate me into letting him stay up a little longer by jumping into my arms and wanting me to hold him......which he never, ever does, until it's time for bed!!! And, of course, I just love it 'cause I never get it! My husband knows this and tells me to stay out of the room while he puts him in his bed. He never gets out when my husband puts him to bed. We haven't had too many probl. Of course, we only have one child so that makes it a whole lot easier. Good luck! Hope this helps!