PMS? Yeah, I'm clueless

I realize 90% of 8th grade girls could answer this, but please humor me.

How many days prior to the start of menstruation does PMS usually hit? I never had PMS before DD was born. ?Since then, I've noticed the day or two prior to my period I am an emotional wreck (DH would probably use another term). ?But I'm at least 8 days away as of today and I'm bloated, backed up and fighting my dogs for the tortilla chips I dropped on the kitchen floor. ?I googled and it just says vague things like "the days leading up to menstruation". ?

Does it usually wreak havoc this early??