First of all, closing the doors is a safety measure in case of a fire. When my son was moved to the toddler bed we used the gate, but once he started climbing/knocking that down we shut his door and put a door knob cover on the inside so he couldn't open it without help from us. We continued to use the monitor so that he could call for us if he needed anything and we could hear what he was getting into. We childproofed his room and only left books and his little touch leap pad in there for him to play with. He did very well, but he's a naturally good sleeper. He was about 20 months old when we moved him. I don't think that 17 months is too early, but there are some people who think you should leave them in the crib until they are 3 years old. I think that's a decision for every family to make and if he is climbing out it's a good time. I would recommend trying to shut the door, as I said, for fire safety reasons and that might help you out.