I agree wtih SyntaxGlitch and cyborg_mermaid, you really should wait until you actually see the movie before doing any cosplay for it.
I guess I can understand if you want to go ahead and start working on it, but first off, there really isn't enough images to accomplish a good accurate costume of any of the movie outfits right now. Its better to wait for more stuff.
Hey, I'm not saying you shouldn't do it, I mean, I myself am planning on doing the costume too but I'm not going to even start working on it until after I've seen the movie, to make sure I really want to do it and all. Plus, I got a bit annoyed that so many people cosplayed FFX-2 before it even came out in Japan. That just shows that they're not really doing it because they love the characters or the game, but because they want to be the first people to do it.