My DD went in at 15 mths, we had the bed set up in her room because of DS' impending arrival, and she chose to go in there earlier than when he arrived. It was low to the ground but you will probably find that she will sleep better in the bed. As long as you have things set up it will be fine. We also have our DS on a mattress on the floor now - we haven't bought his new bed which is coming next next week but it worked well because it is a bed sized mattress and low to the floor.