Kingdom Hearts II When did everybody first obtain Antiform?

Timeless River, right before a cut scene.
I'm fighting, Sora goes anti and I freak out.
"Holy mother****ing ****, he's a heartless again!?"
At first I thought it had something to do with Timeless River, then I remember KH1.
And then during the cutscene, I was like "What the hell? Sora turns into a Heartless AGAIN and no one says ANYTHING about it?"

 

I'm not sure if it's the same as "obtaining" but I discovered it my first time against Demyx in Hollow Bastion, I didn't know anything about it... so when I tried to go into Valor Form and whoop him, I turned into Antiform instead... first thing that ran through my head was. "I thought Riku was good now! What did you do to me, Riku?!"

 

I got it early on when fighting the first boss in Beast's castle, really annoying because it always kills you if you go into antiform V_V

 

i got it in the middle of Saix battle i was all like "why the heck am i shadow sora, and why am i giving off shadow streaks? do i smell bad?"

 

When fighting Xigbar. I was trying to get Final Form actually, but a black guy appeared instead.

 

How early on?

Umm... I think it was somewhere in... Land of Dragons, first visit. Yes. I'd used Drive about once. Since I like the ability to throw loads of punches in a short time (and also demonic possession and such weird things), I was grinning with glee the entire fight. No healing? Who cares when I can kill these things before that matters?

Then the cutscene brought him out of it, and that was depressing.

 

I was fighting random shadows and neoshadows outside memories skyscraper and it happened and i was liike ''D: WTH!! Is this meant to happen?'' x3

 

Got it while fighting Xaldin.
I was like, "FFFFFFFFFFFUUUUU-"