Ralph Waldo Emerson (1803-1882), perhaps best known for his essay Self-Reliance (1841), was one of America's most influential thinkers and writers. After graduating from Harvard Divinity School, he followed nine generations of his family into the ministry but practiced for only a few years.
The first menstrual period is called  menarche .. The menstrual cycle is about four weeks long, starting on the first day of bleeding and ending when the next period begins. However, it can vary greatly when a girl first starts her period. It may skip months or come several times per month in the beginning.
Anyways you count from the first day of your period until the first day of the next one. Well since day 1 is when you start your period 28 would be your pick......however, some cycles can last up to 32 days or more, so there's really no correct answer here. 28 days. It's 28 day from your first day of your last period.