I started my birth control....

So I have this app called Spot On by Planned Parenthood and I started taking my first hormonal birth control on the 17th of April which was the last day of my period. And I have the placebo pills that I have to take at the end of taking the regular birth control the only thing that is making me puzzled is that my period is expected on the 11th of May but I start the placebos a couple days earlier. Is that normal or should I speak to my doctor about it?