<p>Frosh is not compulsory, but some programs do have compulsory stuff prior to the start of classes: e.g. anyone taking a first-year French class usually must do placement testing prior to classes; in music, placement testing in theory, history, keyboard, aural etc. is held well before classes begin and ensemble auditions are normally prior to classes; some faculties have orientation sessions prior to the start of classes (although some of the orientations could probably be missed–son’s roommate arrived 9 days prior to classes to fit in engineering’s orientation only to discover it was essentially a way to encourage first years to do Frosh); and move-in day for residence is usually a week to 10 days prior to the first day of classes. </p>
<p>As FreedayFF mentions, it is also a good idea to arrive early to deal with all of the bureaucratic stuff even if your particular program and classes do not require attendance at anything prior to the start of classes.</p>