Thanks Satya, this is a very good question. But it isn’t that easy to answer as it depends on the child, parent, teacher etc.
The best answer is to start as early as possible. Little puzzles and fun games can be given to the very young children, once they are familiar with the basic number concept (units, tens etc.). So, ask ‘how old are you?’. Double it.
How long til your favourite TV programme – How many minutes is that?
That’s an interesting number on that car. Add up its digits. What change shall I expect from this purchase?
Questions can be relevant/topical. But for the young child is is imperative that it is approached in a fun way, as a game. Children are keen to show off their abilities and should be praised whenever possible. We must not see learning maths as rigid – just the opposite.
This VMTTC course does not start off at such a level though, the reason being that my own experience mostly starts with older children. If you want to teach VM you will need to decide what ages you will accept, and you could accept 5 year olds or even younger.
If the question is, at what age can children be taught the methods on this course, the answer would be about 8 years for the early parts of the course. My three Teacher’s Manuals were written to provide structured lessons for teachers of children of different ages.
I also recommend the work of Vera Stevens. See:
This is great for very young children and Vera has also had amazing successes with children with all sorts of difficulties.