For optometry schools such as SCCO, which admit students based on rolling admissions, then it's definitely an advantage to apply early because there are more slots available...at SCCO there's only 98 slots. If you apply really late, then you're at a disadvantage even if you have stellar stats, you might not be admitted due to the 98 slots taken, which may automatically place you into the alternate/waiting list.
From what I know, at SCCO, just because you're invited for an interview does not mean it's a shoe in...although you are considered an academically competitive applicant, you still have to perform well on the interview to get into the school.