C.M.
My daughter was 20 months old when she learned that she could climb out of her crib and onto the attached changing table. Because it's a convertible crib, removing the changing table was not an option.
That was a month ago and we moved her to a toddler bed and the transition has gone very well all in all. However, I still rock her until she's very sleepy then put her in her bed and rub her back or just sit in her room for awhile.
I have heard of some people moving their kids as young as 13 months to a toddler bed!
My recommendations would be:
1. Crib tent - if you like these. I was not a fan because I felt like my daughter would feel caged in.
2. Toddler bed - I recommend closing the door or putting a gate on the door.
3. Toddler mattress on the floor (to get her used to a new sleeping arrangement but not yet a toddler bed).
4. Twin or larger bed (if you'd rather) with a rail.
Good luck!