I thought about starting Lilly on a little cereal soon, but I think we are going to wait until at least 6 months. Everything that I have read says that solids have nothing to do with getting babies to sleep longer, but I know you can't believe everything you read. I never noticed a difference with ODD. When we start solids, I am going to switch Lilly to formula, so I think we are waiting until she is at least 6 months. We are going to Florida in Sept and I don't want to have to deal with bottles and all that on the plane, so I'm planning on starting everything shortly after we get back from our trip. She will be about 6 and 1/2 months then.