When should someone start working on bone strenght?

When you  see the negative results of not working  your bones and also if you notice your strength in your bones  isn't as strong as they once was.

You should always try to keep your bones strong and healthy, building up the calcium by drinking milk will help keep them strong. After a bone is broken and is mostly healed you should start working on bone strength to make up for the time it had been rested.