Knows the addition and multiplication tables cold
If you know the addition and multiplication tables cold and is in at the least fifth grade, then start with Life of Fred: Fractions. Your child will learn why it is important not to run while carrying an 18" knife.
There is no hurry! It would be a mistake to push kids into Life of Fred: Fractions before they are developmentally ready.
Students of normal academic ability and drive who begin Life of Fred: Fractions even in the 7th grade have a decent chance of starting college calculus (Life of Fred: Calculus) before the end of their high school years.