When should we start our child on foods other than formula? He is almost 4 months old.

4 months. Four months is the age at which we discuss beginning solid foods in infants. Before that (unless a baby has severe reflux and needs cereal) it increases the risk of developing food allergies. It is not mandatory to begin solids at four months...You can air til later if baby is sleeping well and gaining weight well. Begin with greens like avocado, beans and slowly introduce fruits as they are sweet.