Short answer is that it should be fine to use partial GPA as well. It's nothing abnormal as an international student. After all, if you want to start the Masters immediately after the Bachelors, the application calendar urges to apply in December latest. My statements apply to programs with different schedule for domestic/foreign students.
On the other hand, most important downside is that you may miss some classes compared with other applicants. Stating that you are attending a course in the future is not strong enough in many cases.