Do residencies look at Step 1 dates (can they even see that)? I have the option of taking my step 1 in a few months later than normal through taking a research year. If that were to occur, would they expect a higher score from me?
Several schools have their students take step 1 midway through third year as opposed to right after 2nd year, and it doesn't seem to hurt. Take it whenever you think you'll be most ready.