Help

Okay,so me and my gf want to have intercource.We both are really scared of pregnancy as it is not in the cards atm,im 21 and she is 18.

We are going to use a condom from the start as well as plan b.I know if the condom is used right there is no need for the plan b.Its just to be safe.

She is off bc so im scared of her ovulation and something goes wrong plan b won't help.

How safe is it and how can we know when she wil ovulate or already has.