When is the onset of...?!
Question: schizotypal disorder?
Answers: schizotypal disorder?
Like the first poster said, the experts wait before they give a definitive diagnosis for the child to be in his latter teens.
Why they wait so long, beats me. They could be starting the younger person on correct medication and therapy from the get go and save suffering and interference with a normal, happy way of life.
There is no exact onset age. However people are not diagnosed with a personality disorder until they are adults (usually at least 18 y/o). Most of the time children who end up with a personality disorder diagnosis will be previously diagnosed with one or more childhood disorders.