just a correction to Ben Torah:
many, actually i think most bnei askenaz (the term rav mordche shwab used for yekkes) start talleisim way before bar mitzvah some start at age three. also it used to be that everyone wore talleisim before the chasuna the reason why most people today dont wear a talis till their chasuna is becaue they didnt have money to buy one and it became a chasuna gift from the kallah