 [ Symptoms ] is it okay to mix rice cereal into a 3 week old baby is bottles [ Disease ] i generally recommend holding off on introducing cereal until 6 months of age 3 wk olds who drink breastmilk will want to eat every 1 5 to 2 5 hours and those who are formula fed eat every 2 5 to 3 5 hours that usually feels to a parent like they are not sleeping much and eating a lot  in general i would enourage you to stick to breastmilk or formual at this point and feed on demand 