Was in your exact same situation. Green card took longer than expected for many of my acquaintances, so I decided to wait until I had it in my hands to register for the MCAT. It ended up taking two years longer than expected so it was the right choice for me. I guess my advice is to make sure that estimate of yours is certain first, then decide when to take it. And you're right, do NOT apply as an international student. It's incredibly weighed against you. Good luck!