The committee, consisting of faculty from biology, chemistry and physics, writes a single letter of recommendation from the college. Arrange for 3-4 other letters that say different things related to your experiences in health care, community service and other activities. The earliest you may apply is at the end of your junior year, 9-12 months before graduation. Applications from students who have already graduated are much stronger. Apply between June 15 and October 15.
Earlier applications have an advantage.
If you are an Oregon resident, apply to OHSU and to 10-15 private schools. Consider also osteopathic schools. To major in biology, consult with Dr. Southworth. To major in chemistry, consult with Dr. Keevil. Other majors should see a departmental major and Dr. Southworth or Dr. Keevil.