Generally, it is 28 days, but it can also be longer. On a 28 day cycle right around day 14 ovulation happens and the ovum is viable for a 5-6 days in the uterus, so if you have sex from day 11-20 it is possible you can get pregnant. Sperm can live in the uterus 5-6 days and this has to be taken into account when counting days of a cycle.
28-35 days
Up to 7days but every girls period varies.
That differs between every girl so I'm sorry but no one can give you that answer.There are girls that are flatchested that have had their period for years.
Between 10-16.
Most girls will have their first period between the ages of 11 and 14. But some girls will start as early as 8, whilst others may be as late as 17.
Girls usually get their first period between the ages of 11-15.
All girls get the period
The gap is not fixed. Different girls will have different time periods in between, depending on hormonal levels and genetics.
Puberty - in girls, it generally occurs between ages 9-11.
28 days
All girls get the period
about 28 days
I would say about between the ages of 11 and 13