Our kiddos sleep in their cribs until they are 3 years old. Moving Keandre out at 35 months was early, in our minds! I guess we've been blessed with kiddos who aren't into climbing out of their beds since he was the first to do that, and we pretty easily convinced him that wasn't a good idea. Ultimately, though, we wanted to give him plenty of time to transition to his new bed before his baby sister made her arrival.
Not surprisingly, he loved his big boy bed! But we soon decided it would save space if he moved to the bottom of the bunk bed. So just one month later the toddler bed was taken apart, and Keandre joined the big boy world of twin-size beds. He even has his own little shelf to keep his books on.