DD started his math competition when he is 4th grade. He joined Math genius contest and got the 2nd place. The thing he likes most is that he got $40. He said that this is the first time he earns money. Since the competition fee is $15. So he earned $25.
Now he has several years of math learning experience. He started to do AMC 8 and mathcount.
The experience I have is to start early. His sister is alos good at math. But when we realize it, she was already in middle school. So she was making the decision that math is for nerdy only.