I didn't call it weaning b/c DD still took formula until she was 12 months old, but yes, we introduced baby cereal around 4 months. Then around 5.5 months, some fruit and continued on slowly to veggies, etc. So if he appears hungry, even with his milk feeds, and is interested in your food, holds his head up well, and doesn't thrust his tongue out when you put a spoon in his mouth, he may definitely be ready to try the baby rice cereal. If rice constipates him or he has any trouble, they have baby oatmeal and barley cereals as well. Just remember to try only 1 new food at a time over a span of at least 3 days to rule out any allergy or intolerance.