Our son is now 6.5 months old and we are wanting to start sleep training. I am not so worried about him crying when we put him in the crib however I am concerned he will just play. He's starting to sit up and goes on his hands and knees a lot. Does anyone have any suggestions for making this sleep training a success? Did we wait too long? Should we have started sooner? I just always read the CIO method should not be used until at least 6 months. Any thoughts or suggestions would be greatly appreciated.