Audition rotations are a pretty big deal for D.O. programs. Not so much for MD residencies.
Typically schedule them between August and December of 4th year.
Some advise that if there is a program you are really interested in you should try to audition there.
I personally think that auditions have a greater chance of hurting you than helping you unless you are a clincial rockstar who can keep up an optimistic/enthusiastic appearance the entire time you are there.
My 2 cents