Boob pain: PMS vs Preggers

For those who have been pregnant: how is nipple/boob pain different than PMS nipple pain?

Typically my nipples are tender/sore a week before my period then goes away. But this month I’m having random sharp pains deep is my first month off birth control so I don’t know if it’s hormones or (hopefully) baby. I’ve heard your boobs are SO sore when you’re pregnant, but when does that start?