Hi, i took a plan b pill last month and my period came a week early. will my ovulation time be 14 days from when my last period ended even though it was early or will it start from when my period should have ended?

It is difficult to say at this time. Plan B would certainly be capable of altering your normal cycle. It may make it early or late. Without continuous testing and monitoring (which is not necessary) it would be impossible to predict

light bleeding is associated with estrogen withdrawal from "Plan B" contraception, so the "early period" may not be accurate. Plan B is not 100% effective, so wait a week and obtain a serum HCG test to be certain about pregnancy. If negative, see your GYN about low dose oral bcps. The "14 day" time is the time elapsed from ovulation to period onset (in the absence of pregnancy) .