What age did you take the sides off the cot?
We never did! Moved DD straight to a king single a bit after she turned 2. And only because we wanted to transition her before #2 arrived. She made the move very easily. Was previously in sleeping bag but now sheets and no worries. We don't even have the side barriers on the bed, it's fairly low but she's never fallen out.
Re: What age did you take the sides off the cot?
If shes not a wriggle pants you should be good to go :) they can get excited about changes at this age too, so cute.