Originally Posted by AnthroMD

Your letters will most likely not be looked at until you have submitted your secondary. After they receive your secondary they will begin to review your completed file (including your letters) to determine whether or not to send an interview invitation. However, some D.O. schools (LECOM) will extend an interview invitation after receiving the secondary and prior to receiving your letters.

Since you are using Interfolio, keep in mind that it takes time to send letters to an application service, upload them, then have each school download them for your file. So as soon as you receive a letter, send it off. If you are applying MD, it would be loads easier to just have them upload the letter directly to AMCAS that way there is no lag between Interfolio-AMCAS. I applied MD and DO and kept everything separate. Direct upload to AMCAS for MD (obviously) and Interfolio --> each D.O. school.

Hope this helps. Good luck!