it really depends on the school. amcas has a specific deadline in the fall, but most individual schools that use amcas also have secondary applications, some of which are due in the spring.
foreign medical school run on totally different schedules, so you'll have to look at the specific school websites to find out when applications are due.
All schools will have their own deadlines for submitting the primary and secondary application. When you add a school on AMCAS, it'll tell you the latest date the school will accept apps.