at my current airline, POLAR, a lot of pfe's don't have their pilot licenses, but they do have their a&p . we have also a few fo's and captains that got their a&p, took their fe written and got hired as pfe's. then started working on their licenses from private to comm-mel-inst. they bought fligth time and when they meet the req. for fo change seats. others , instead of buyin time, did instructing on the side, then took LOA to go to the regionals and/or 135 turbine jobs and less than 2 years later went back to polar for the fo position.

hope this helps