My son is breastfed but he started cereal at 3 months I did oatmeal since rice constipates and then he started fruits and vegetables at 4 months! He loves then! And he hasn't had any constipation issues really, and if he does seem to be stopped up I just feed him prunes he loves them and it works for constipation! I also don't give him a bunch of bananas cause those can constipate as well