At what age should we start teaching the children praying?

At the age of7 they should be ordered and motivated and at the age of10 they should be punished if they are careless in this aspect (this specification is present in a hadees of Mishkat)

I agree with the answer given by Bilal Hashmi. I would just like to add that those ages (7 and 10) are measured by the lunar calendar not the Georgian one.