J-1 students must be enrolled full-time each academic semester. Full-time is defined as twelve credit hours per semester (Fall and Spring) for undergraduate students. Full-time is defined by the academic division or school for graduate and professional school students.
Dropping below a full course load is a violation of your immigration status. There are limited exceptions to this rule, but they require authorization by an international student advisor before the drop may occur.
As a J-1 student, you are also required to make normal progress in your studies.