I know for me, the dysphoria might have always been there, but it would have been a fog of sorts. A faint feeling of discontent without being able to pinpoint why. I'm nonbinary, though, and we don't really get inundated with images of what our ideal bodies might be like the same way that... men and women do, lol. It's like looking into a mirror and not having a reflection. Now that I have a more concrete idea of what I could be like, I've started to find that I do experience some mild body dysphoria now. I hardly wear regular bras anymore because I like the flattened look more, and I've found myself starting to imagine what it would be like to not have a vagina.
But it's likely very different if you have people you can point to in your life, images on TV, in magazines, in movies, and say "I want to be like them" from the moment you have the motor skills to point. I never had that.
ETA: And oh, that's a great little list, Sephirah.