C.P.
Our son was 16 months old when we had to transition to a toddler bed for the same reasons (he actually climbed up and over and had a nasty fall out of his crib). It took us about a month. We started out by rocking him to sleep for a week and then carrying him into the bed. The second week we started just laying him in bed and reading stories and staying in there until he eventually fell asleep. We continued with that for the rest of the month and after that he was fine. We also immediately bought and put up a nice gate for his bedroom door. That way if he did get out of bed, he couldn't leave the room, so we didn't have to worry about his safety. We child-proofed his bedroom... and basically turned the entire room into the "crib". After that first month, he was doing great in the bed. Good luck!