There is a book Teach Your Baby Math that uses a technique with red dots to teach counting, addition and subtraction that you can start at 3 years of age. Ano

There is a book Teach Your Baby Math that uses a technique with red dots to teach counting, addition and subtraction that you can start at 3 years of age. Another book by the same author called Teach Your Baby to Read shows you how to teach reading and foreign language. They recommend earlier ages as the mind is still developing and has 3x the neural connections. Good habits like washing hands etc are something you can teach at a very early age and are actually encourage in Montessori schools. By age of 6 it is much harder to establish good habits.