I'm just wondering what's the average age to move a toddler out of the cot into a big bed? We don't have a toddler bed and aren't planning on getting one but we have a single bed. I said to DH that it's probably a good idea at first to just put the single mattress on the floor and then after a while set up the bed properly when we move DD out of the cot...I just don't know when to move her out of the cot or when to move the mattress off the floor onto the single frame.

DD is 15.5 months old.