The timing of the test won't matter. And you will be compared to other foreign md's no matter what, there is definitely a preference to us medical students...anyone who passes step 1 here is able to get a residency immediately after completing school so long as they don't have their sights set too high and apply to places within their means.
As far as any impact on your score in terms of when you take it, it should not matter much and in either case it is kind of random. The test given during a certain time period might be harder for whatever reason, but it is luck of the draw. The scores are not curved, but instead they try to make the questions about equally hard on the whole for all the exams. For example, if they were to use a scale of 1 to 5 to rate difficulty of questions, and if one exam had 60 5's and 100 4's and 100 3's and 50 2's and 40 1's, then they would go for that same ratio for all the tests. How would they determine what question is a 5 level or a 4 level?? They probably first use new questions as part of the experimental pool (supposedly 50 questions on each exam are experimental and don't count), and based on what percentage of students get them right on an experimental basis, they then use that to estimate how difficult the question is.
But you can see how a system like that would create problems. A question about HPV's involvement in cervical cancer 10-12 years ago may have been a level 5 question because it was pretty obscure back then how strong the link was. Now a days, that would be a level 1 question, everyone knows HPV's implication in cervical cancer...Also, medical school curricula change over time....The bottom line is sometimes luck of the draw plays it's part, so you can try praying that you get a good exam...
