Plan B

I looked in the memories and could not find anything in them for what I'm about to ask,

My boyfriend and I had sex for a week after my period, one thing lead to the next, I took the Plan B pill.  As usual, it makes you bleed to flush your system.  I am leaving for Savannah for St. Patty's day, coincidentally I will be starting back that weekend.  Is there anyway that my period will be on the same track that it was before I took Plan B?  I've done some research on this topic, but was unsuccessful on retrieving the answer exactly.