Medical scientists usually need a doctorate degree in biological science. Some medical scientists have medical degrees. Medical scientists typically complete courses in biology, chemistry, physics, engineering, mathematics, and computer science.
Status: Medical Student (Accepted) AMCAS states that it usually takes ~4-6 weeks for verification to go through, but looking at the verification trend right now here: http://forums.studentdoctor.net/threads/2014-2015-verification-thread.1076112/ I would say you're looking at 3-4 weeks from the time of submission.
Once the board of nursing declares you eligible to test and your ATT is issued, you must test within the validity dates of your ATT nursing (varies from 60 days to 365 days; however, the average is 90 days). These validity dates cannot be extended for any reason.