My 6 month old has 28 ounces a day. His doctor okaye. d and even insisted on starting rice cereal at 3 months. by 4 months you could maybe start an apple sauce or a peach sauce but only do 1 new food a week. I have 2 boys and both ate solids by 3 months per their pediatrician saying to do so. My 6 month old is just now trying mixed foods including puree meet.