All three, lol. I knew I was bi from a very young age. So, I started swallowing my own cum pretty much as soon as I started masturbating. I remember having to forse myself in the beginning, but I eventually got used to it and started liking it. I knew I wanted to swallow another guy's cum, so I didn't want to gag or be surprised by the taste.
It worked, The first time I sucked a guy's dick, I loved it and had no problem when he pumped his cum in my mouth. Even he was surprised by how easily and eagerly I did it, lol.
Luckily, for me, I met the right woman in college. She loves that part about me.