I was advised by the paed to start ds1 on solids at 4.5months as he was a slow weight gainer and had reflux. It helped dramitically with both. I did try him on the rice cereal but he wouldn't have it. So then I started making my own pureed vegies, banana to begin with.
With ds he started solids at 5.5mths. I never bothered with the rice cereal.