I hope your in good practice of doing self-tests already. It's never to soon to start!
I've had to do them since I was 10 years old. If I didn't I would get grounded because my mom wanted to stress the importance of doing them. If I found anythingn I always went and asked my mom to check it out for me just to be on the safe side. I have already gone through a bunch of tests, shots, ultra sounds. I have to start mamagrams at 25 now. I will be going in soon for a cells test, just to find out if I have any of the cells at all.