It can be useful to take the EPPP during the year you are accruing post-doc hours in states that allow it, because you are then clearly "license eligible" when you begin job search during your post-doc year. Also: the ASPPB site is useful but not always entirely up to date, so always be sure to also go specific state Board of Psychology sites to determine the details of timing, length of internship, etc. If you are doing a non-APA internship site, for example, you can learn what is needed to establish "APA equivalency" for that state and get all the documentation in place as you go, which streamlines the application process. For things like this you need to be in direct communication with the specific state board.