If you are unsure about when you should introduce solid foods to your baby, talk to your baby’s doctor before starting solid foods. When your baby is able to sit up and able to grab, this is an indication that they are ready for solid foods.
Some good foods to start your baby on are cereals, oatmeal, and vegetables. When starting a solid food, start only one food for a few days before switching to a different food. This way if your baby is having any problems with solid foods, you know exactly which food is causing the problems.
(Source: American Academy of Pediatrics)