If lifetime risk is high enough (>20 percent) you may consider treatments that can reduce your risk. You would start mammogram screening at age 30 and consider using breast MRI also. Breast exam by health provider is recommended every 6-12 months.
If your risk is lower, then standard screening with annual mammograms beginning at age 40 is recommended.
Breast self exam should be done by all women monthly at the end of menses. This complements mammograms, which can be less sensitive in premenopausal women due to higher breast density.