noFap and Semen Retention

Hey all, so I recently picked up noFap.
I'm curious as to exactly how Semen Retention plays into it. I mainly picked up noFap due to my pornography addiction but I've heard that you can benefit even more by moderating your orgasms. I had sex on about day 4 of NoFap with my girlfriend and I did orgasm but I don't count that as a failure as my primary goal is to just stop masturbating and watching porn.

So my question to you is, how often should I allow myself to finish?
My girlfriend is supportive of the whole semen retention thing but dosen't want this to be something permanent. What is the best way to learn to have sex without ejaculating?