Hmm I totally understood. Well to be honest I didn't realize that, but that small black flash between the init and the fading, do you know how to even remove it ? x) Because that's what makes it unclear for me.
Anyways, try to go into Cinematic Mode, then take a screenshot of the fade (So the in-game UI won't interrupt or interfere, it'll be replaced by Cinematic Borders), then when you take the screenshot, try to replace Cinematic borders by black void. And use it as a Loading Screen. Otherwise the loading screen will be resized vertically.
That'd do it, hope you got it after all, it's a bit complicated.
Regards