I am in the Army. I am a GMO/ Brigade Surgeon who is going back to GME after spending 2 years in the operational army. Maybe my orders came early because even though I have to do so much of my 1st year over after changing specialties(it will be like being an intern again, only I will be a CPT that is close to pinning on MAJ), I am technically a 2nd year resident. Also- I demanded that my Branch manager get those out to me ASAP (some people that were leaving after me already had their orders).
Let me say something else to you to help you put your mind at ease- you know more than you think and everyone is going to be in the same boat. You will learn what you need you as you go through your first year. You will have to take step 3 in your intern year - so study for that (I am lucky in that I already passed it).
Right now as a 4th year- you should be shamming and having fun. You sill never get the opportunity to sham so much again in your life. Go out, Party, booze it up, go on a trip- what ever. Personally- I recommend that you not even read until the first day of internship- you will be reading the rest of your professional career.