With my boys they were 3, and almost 3. Both never climbed out of the crib. With my older son, he started napping on the single bed first at about 2.5 and by 3 he was sleeping in it at night. With my younger son we were staging our house to sell and rearranging rooms and decluttering and took the crib down as part of it. He was 3 and a few months.
My daughter went into a toddler bed at age 2 (again to do with moving) and I have regretted it ever since. I should have left well enough alone!
Personally, I wouldn't rush it!