Not knowing when the DO match is, I can only offer generalities. In GENERAL, you want to do the audition early enough in your 4th year that you can complete the rotation and allow the attending(s) to write you LORs which make it into your file. Therefore, summer/early fall is the preferred/hot time for audition rotations. If your match deadline is later than November 1/December, then adjust the schedule accordingly.
Hope this helps.