I received a 22O on the MCAT, lower than I had expected. I have a cGPA of 3.5 with decent/good extracurriculars.

Do I apply to Carib schools now, or wait 2-3 months when I get my next MCAT score? Do I have a shot to be matricualted in the upcoming Fall 2011 or Spring? Which semester should I apply to begin?

If I were you I would wait and improve the MCAT score. Seems like you would have a shot at MD school in the US with higher MCAT. If you're set on SGU, it would probably still be better if you waited for your next MCAT score to apply.