My answer on Quora:
Thank you for A2A.
USMLE step 1 consists of basic sciences subjected that you have studied in 1st and 2nd year of MBBS. The eligibility to give a USMLE exam is being enrolled in a college registered with IMED-FAIMER.
This is the link of the directorysearch if your college is listed in this directory.
Thus, if you are both a medical student from a IMED registered medical college and wanting to study for USMLE step 1 then you can give now after preparing for a few months.
When to start applying and taking up electives?
Now is the time.Once you are a medical graduate, you are not allowed to apply for elective. You can only do observerships or externships. Difference is in the quality of clinical experience and LOR you get.
Hope that helped in clearing your doubt. Let me know if you have any further.