My grandson was an early climber, and Mom and Dad had already decided the first time he climbed out of his crib they would convert the crib to a toddler bed for that night. (They wouldn't use a crib tent because their pediatrician had a patient who strangled to death in one while trying to climb out of their crib.) My grandson was 17 months when he got his leg over the railing and fell. Mom was devastated, she didn't use bumpers or extra blankets to give him leverage, and the mattress was as low as it could go. Dad got out his tools and converted the crib into a toddler bed within an hour.
What they did before that day was to make sure they had childproofed the whole house including his room, so he couldn't climb furniture or strangle himself in cords from the blinds, they covered light sockets, puts toys other than stuffed animals and some books high in his closet where he couldn't reach them, door knob covers on the doors, etc., and had an extra baby gate to put across his bedroom door for the expected walk outside his room if he got the door knob cover off. They wound up stacking a second one on top of it because he did eventually work the knob cover off and as I said, he was/is a climber.
They liked the toddler bed for him, because of his young age at the time he began using it and since it was smaller than a twin he felt more secure in a "little" bed, and they weren't worried about him falling out and getting hurt. But, since they had it already there wasn't an additional cost at the time he began to use it. Around the age of 3.5 he transitioned into a twin bed they'd set up for a houseguest. She left, he took a nap in it and it became his new bed.
Bottom line, do your childproofing now if you haven't already, so you aren't caught off-guard. Let him start taking naps in his new bed once you have it set up so he becomes accustomed to it. Your routine can and should stay the same, if you stay in the room with him he may get used to that and be unable to continue to put himself to sleep. If you handle it as matter-of-fact as possible so will he.