Babies are ready to eat cereal when they can sit up and keep their heads up, typically at about 4 months of age. A baby who is ready for solids can also move food from a spoon into the throat without dribbling all of it back out of the mouth.
When first introducing cereal, select a single-grain variety that is intended for babies. Thin it out with breast milk or formula, and serve the baby one tiny spoonful at a time. Serve it at the beginning of the feeding, when the baby is the most motivated to eat. Speak to a pediatrician before introducing cereal or any solids to a baby younger than 4 months of age.