the caller must be an adult in knowledge and permission and if he is less than that then there is no problem as long as he is knowledgeable in general and the same applies to the wing.
ولا بد للداعي من أن يكون بالغا في العلم والمأذون وإن كان دونه فلا بأس بعد أن يكون عالما على الجملة وكذلك الجناح