When did Jesus say its time to be about my Fathers business?

Jesus was twelve years old when His parents travelled to Jerusalem for the feast of the Passover. Afterwards, the group departed and travelled a days journey before they realized Jesus was not with them. When they went back to look for Him, they found Him in the temple, sitting in the midst of doctors, both hearing them and asking questions. When Mary asked Him why has He done this thing Jesus says in Luke 2:49 "How is it that ye sought me? wist ye not that I must be about my Father's business?''