If you'd like to work quickly, you can take your clerkships concurrently with your coursework. If you'd rather extend the work over more time, you can take your clerkships after your complete your courses. Summers are another variable to consider. Core coursework will not occur over the summer. You may find that taking rotations in the summer works for you.
Summer is a good time to think about experiential clerkships.
You could take as little as one credit or more, depending on your other responsibilities. You could work in your place of employment on a practice enhancement project or at another site providing patient care. If you are planning to complete the program in 3 years, you will probably want to think about taking at least some rotations in the summer. The actual cost will depend on year of entry into the program, speed of completion and prior learning. It's important to think about costs on a term by term basis versus a lump sum.