My daughter was able to sit up on her own, hold her head up, and not spit food back out at 5.5
months so we started solids. We also let her have a bit of water as well as
breast milk at 6 months. New recommendations are you can introduce cow's milk any time between 9-12 months rather than switch to formula. But it should be the 3.25%.
Also rice cereal doesn't provide much nutrition and my doctor said to give meat purees like chicken and beef as first foods. Eggs too.