That's only if you're a Sunday starter. They have two methods for starting your pack, and one of them is to start the first day of your period. That's what I did, and I'm having a super-heavy-long period right now, too.
I was on Yaz for a while, then off it for a few months, and I just went back on. I remember the long period happening last time, too. It'll even out after a while.
You weren't supposed to start taking it on the first day of your period. You were supposed to start taking it on the sunday after your period ended.
i took YAZ for a while and my periods were longer and heavier at first too... they normal out though after a couple periods!
I am experiencing the same thing. Did your's ever stop after going through it for a couple of months?