Asking now the Medium or Psychic learned their craft is important also.

I’ve seen psychics spread out tarot cards before picking up a book to disclose the meaning. Regardless of the individual’s age, this is not a
psychic nor a medium. No two people’s tarot cards will read the same, every card has a special significance for every individual.
Just like each person’s interpretation of a two of cups or a five of swords is unique. 

You cannot become a Medium or a Psychic by reading a book.  

You can have a reading at any age. In fact, I am even able to provide you with a message from your unborn baby. This can be between the first trimester to speaking age which is toward the end of the toddler stage. After that stage, the child will need to be of an age where they can provide consent for themselves. Unless you may be requesting a reading for example, a lost child or a child whom has passed over, then readings with children from about 3 to 10 are not generally performed.