Is it normal to get your period one week early?

First off, I’ve been on Yasmin for almost 2 years now.
After this period I’m supposed to switch to demulen as Yasmin is no longer doing the trick.

This has never happened to me before, but today I realized that I got my period a week early is this normal?
and since I’m on the last row of the yasmin before the sugar pills, do I still continue to take the pills or do I stop??