Mediocre is general at best. However, I would say that if you are TRULY mediocre applicant which by my standards is probably something along the lines of less than a 500, less than a 3.5 cGPA & sGPA, with some combination of less than 1000 clinical hours, 250 volunteering hours, 50 shadowing hours or close to these numbers, then my first advice would be don't apply and my second advice would be before October 1st but preferably before September 1st.