For MOST schools... Prereqs must be done prior to the summer of matriculation. However, it seems not all are so kind,
"
A minimum of 3 years college course work completed in a U.S. or Canadian college or university is required. To be considered, an applicant must have documentation certifying completion of a minimum of 90 semester credit hours at the time of application.
The college work must include:
English Composition & Rhetoric 6 hours
Biology or Zoology (with Lab) 8 hours
Inorganic Chemistry (with Lab) 8 hours
Organic Chemistry (with Lab) 8 hours
Physics (with Lab) 8 hours
These are firm requirements regardless of undergraduate or graduate preparation."
that is from WVU dental school. So do not apply there.
Good luck!