4yr (2yr to menses)
A girl's puberty
lasts about 4 years overall, but the range can be from 1.
5 to 8 years' time. Her periods start about 2 years after puberty begins. The later her puberty starts, the shorter the time between the beginning of puberty and the start of her periods. So, a girl who starts puberty at 9yr might have her period 2yr+9m later, but a girl who starts puberty at 13yr may have a period 6m later.