Praise be to Allah.
It is not permissible for guardians of orphans to give them their wealth until he feels that they have become mature, i.e., that they will conduct their affairs well and not spend it on haraam things. The time for giving it to them is not when they reach adolescence, rather it is when he feels that they have become mature after they reach adolescence. Allaah says (interpretation of the meaning):
“And try orphans (as regards their intelligence) until they reach the age of marriage; if then you find sound judgement in them, release their property to them”
A person is no longer considered to be an orphan once he reaches adolescence, and adolescence is recognized by a number of things: the growth of coarse hair in the pubic region, reaching the age of fifteen, and emitting maniy (i.e., reaching sexual climax) whether awake or asleep. It is the same for both men and women, except that there are two additional signs in the case of women, namely menstruation and pregnancy. It says in al-Muqni' (2/139): “Adolescence is reached when a person experiences a wet dream, or reaches the age of fifteen, or grows coarse hair in the pubic region. In the case of girls there are two additional signs: pregnancy and menstruation.”