Apply ASAP, I applied for Next Fall's classes at SGU and AUC even before my MCAT scores were released last Oct (took Aug MCAT) They way I see it since they have rolling admissions once people get rejected from al the schools they applied to they will start looking for alternatives and the best alternative for US students if they don't want to wait is to apply to Carib schools. Thus come spring time many more people will be submitting their apps and a higher competition among applicants will force the adcom to reject someone who they would have accepted two months earlier if they had just applied earlier.
On another note I only applied to SGU and AUC because of the policy made by Ross to force a student to repeat an entire semester if they fail just one class during that semester, thus if you fail say immunology but pass all the rest of the classes that semester you still have to take all the classes you passes in addition to the one class you failed. I personally think its kind of ridiculous but hey what can you do right? I don't plan on failing a single class but sometimes things happen beyond your control and I would hate to have to repeat an entire semester because of one class and pay an extra 20K.