On average, a 5-month-old baby should start with 1 teaspoon of rice cereal per day. They should not eat this dry, but with 4 to 5 teaspoons of their regular formula or breast milk. The mixture should be very runny so that the consistency is close to milk, making it easier for the baby to eat it.
Once the baby tolerates the rice cereal well, increase to feeding him or her 1 teaspoon of the cereal twice per day. With every serving, the rice should have 4 to 5 teaspoons of formula or breast milk. Gradually reduce the amount of fluid and increase how thick the cereal is. If the child does not take to the cereal, keep trying every few days until he or she starts to accept it.