Understanding OPKs

Hello- I am looking for some understanding. I have been averaging a 30 day cycle and was supposed to start day 1 on 11/26 (period) but have been using OPKs daily for about 1 week to better understand my cycle. Today was the 3rd day in a row that I got a (very) positive result on my opk. Does anyone have some insight on what is going on? Again I have NOT started my period, but am apprehensive about taking a hpt.