Sore boobs

So today I was suppose to start my period but I didn’t, my boobs are starting to become sore though! Usually this happenes a week before I start my period or it also happened during my last pregnancy where I had constant sore boobs! Does anyone else experience sore boobs and pregnant? If so, when did you notice that they were hurting?? Was it before you found out you were pregnant, or did you already know you were pregnant?