There are so many variables and possibilities in this process that trying to figure out “optimal” scheduling will probably do more harm than good. For example, you may catch a cold the day before your very-carefully-scheduled audition date at your favorite school, you may do a spur-of-the-moment walk-in a Unifieds for a school you have barely hear of and decide that is absolutely the best program for you, the department head may announce they are leaving in December, snow storms may disrupt your audition schedule, etc., etc.
Most people try to schedule auditions for the programs that they are most interested in somewhere in the middle of the “season” rather than in the fall or at the very last audition in the spring. Some people think that it is better to schedule auditions earlier rather than later for schools with rolling acceptances. In the long run, it may behoove you to just work out the audition sequence that works best with your senior year schedule and let the chips fall where they may.