When should they begin eating minerals? That's a good question. I've often worried that my little ones might get too much of something they don't need, so I try to keep mine out of their reach. With that said, I've noticed a lot of mine begin eating the minerals by 3 months old....sometimes sooner, sometimes later. Most of the time it is instinct (they will only use what they need when they need it) or they see the others doing it and learn from them.