Birth control, Plan B and odd cirstances...please advise!?

I've been on birth control for the last five months and while I might have a missed a couple days here and there (and subsequently took two pills the next day to make up for it), I've been pretty faithful about taking it at the same time everyday. Unfortunately, the condom broke early Sunday morning as I was on my last day of my period. I was set to begin my birth control pack today, but decided to start early and took two pills last night. I've now hit the 30 hour mark since the incident and was wondering if I was advised to take Plan B just in case? Can changing your start date on your birth control pack impact your cycle and make you more vulnerable to pregnancy?