When it is the best time to tell?

Hey guys,
I am seeing someone that I met last year, we enjoy each other, kiss, hang out, talk a lot and etc. And I am really liking it, but, I did not tell about my PIED, I confess I am kind of ashamed. When we are cuddling everything is fine, it gets hard and I am confident in oral sex, but just to think about penetrate scares me. We never stayed in a place that allowed us more intimacy, but I am really looking forward to sleep together in my place.
My question is, when is the best moment to tell this? How to tell this? We do no talk a lot about sex so I don't ever get the opportunity to bring this subject.

Well talk about sex.  Or choose to talk about porn.  Bring it up in a way that is just you talking.  Kind of like at age whatever, I saw porn the first time and I became very curious..  I kept looking at porn.  I did not realize the effects it could have.  Tell her some of the effects, the effects it had on you. Then, only if you truly want to stop, you can tell her you are trying to stop.  And then go from there.