That is a great question! Because of your family history, you will need to start mammograms earlier than the general population. It is recommended when you have a first-degree relative with breast cancer (i.e. Mother or sister), you should start mammograms 10 years earlier than when they were diagnosed. For example, if your mother was diagnosed at 42 years old, you will need a baseline mammogram at 32 years old. Also, you should inquire if your mother and/or grandmother had BRCA 1/2 gene mutation testing.
I hope this answers your question!