Hey ashish as u told that as the amg comes into the scene is there any differnce in the scoring system for step1.Yeah - I agree - depending on the kind of student you are going into the thing - 6 months give or take a month should be fine if you're an IMG. 2 months if you're an AMG.
What I would do, is, if say, I wanted to write the exam in 6 months, I'd start my eligibility period at the end of that - so for example in your case - 6 months from now is November so March 2011. I'd pick March April May as my block. It's a good block because its before the AMGs join in on the game and also because you'll have a new first aid to help you.