Will my period stop sooner?

If you start active pills sooner than yes, your period should stop sooner. And the thing is that you don't actually have a period when you are on the birth control pills because they stop your ovulation so there is no need for your proper menstrual bleeding that is triggered by ovulation. What you have as a period on a birth control pill is basically bleeding that happens because your hormone levels suddenly drop when you stop taking active pills and that causes so-called breakthrough bleeding. This means that if you were taking active pills with no break (like when you are on Depo shot, for example), your period bleeding becomes lighter, irregular and usually completely stops.