Well, no. The region doesn't need to be canon. And you're free to specify where it is in relation to other regions. The Saro Region is specified that same way.

As for catching up, since we aren't far into the rp by any definition of the word, my suggestion is to just post a wall of text to catch up. We'd assume your character is with the group, as there are nameless trainers who are just kinda there in the group. Something as heavily advertised as this would attract more than 10 people.

I'll also be closing the sign ups soonish maybe, but they may reopen if people drop out. I'll find a way to throw in new trainers that way.