On the day I was to start my period I started spotting lightly it was light pink. Its been going on for 3 days now. What could this mean?

Menstrual period. In the younger age group, the quality and amount of bleeding can vary from one month to another more than the older age group.
Normal. If you are spotting when your period is due, it is probably just your period. If you are unsure and could be pregnant, you should take a pregnancy test.