Start at age 6 months with baby cereal mixed with water or formula
Then try the small 2-ounce jars of baby food veggies. If that goes well, then try the baby food fruits; and later the meats. If making home-made baby food, just use similar flavors as the ready-made jars, such as peas, sweet potato, apple sauce, banana, lamb, etc. Use each flavor 2-3 days before adding a new flavor.