About a quarter of Williams’ applicants complete their prerequisites by the end of the junior year in order to apply that summer, be active in the application process through the senior year, and matriculate immediately after graduation.
About a quarter of Williams’ applicants wait until the end of the senior year to apply, planning, therefore, on one year between college and medical school. Some do this so that they can spread the prerequisites into the senior year. Some do this so that they can study abroad with less scheduling stress. Some have completed the prerequisites earlier, but want more time to focus on academic and extracurricular pursuits. Others simply want a year of doing something different and wish to explore the working world.
About half of the Williams applicant pool begins the process well after graduation, commencing the process two to ten years between undergraduate and medical school. The office works with these applicants by phone and e-mail, and expects that deadlines will still be met. If at all possible, a trip to campus to meet with the advisor at some point is extremely advantageous. There is no stigma among the medical schools against well-motivated older applicants.
Some students decide upon a medical career too late in their college career to complete the prerequisites. They may choose to matriculate into a post-baccalaureate program or simply take the required courses at a state school or university extension program.
This site, maintained by the AAMC, has an excellent list of postbaccalaureate programs to meet diverse needs.