So I got my first period last week and I wanted to wear the hijab but my mum told me to wait until the second term of 6th grade ends which by the way starts next week and I don't think that's a great idea to wait.. and 3 of my friends wear it (they wore it the second day of there first period) but they are 12 and I'm 11 but I'm going to be 12 after the second term ends and I tried to convince my mum to let me wear it now but she won't change her mind.. she thinks I'm too young because I don't wear a bra yetbut I'm not! Do u think if I wait it will be wrong? And what should I do? And plzz tell me when do you think a girl should wear the hijab please tell me an age don't tell me after puberty? I seriously need help!?

You seriously need to follow your mother's instructions/advice. It is her decision to make.