I don't know if there are any second years from UTSW that post in the forums, so I will give it a try. I really don't honestly know the details at all. I know that second years get about six weeks off to study after their second year, and then take it. I found this link where the school sets up study sessions if you want to take advantage. Here it is:
http://www8.utsouthwestern.edu/utsw/cda/dept26446/files/70498.html
Hope that helps, and hopefully someone else might be able to give some insight.