There is a myth that kids who co-sleep stay in their parents' beds until college. It's definitely not true. They will transition to their own beds even easier, sometimes, than children who are sleeping in cribs because they are used to sleeping in your bed. They can get on and off. These children, by the time they are two or two and a half. If you feel like they are ready for a big bed, they can do it. They know how to navigate a bed very easily. They are not having these four walls around them to contain them. So when you put a child to bed, you say, "This is your big boy bed. You are ready for it now." Make a big celebration of it. Chances are, they are going to stay in it most of the night because they are used to sleeping in a bed. Children that have been sleeping in a crib, they are up all night realizing they suddenly have freedom; whereas, children have already been sleeping in a bed, they had freedom all along, so it's not a big deal for them.