As already stated, there is no flow just a guaranteed interview but you won't be around long enough for that. Which regional probably doesn't matter, Endeavor might care less if you leave right away to Delta since they are a wholly owned, but that won't matter to you anymore as long as you make that jump in the first place. Pick whatever regional is easiest for you to commute to or offers you the quickest class date.

I'm going to add that I'm just going on the presumption that you have someone already who will get your app pulled for scoring internally.