My personal experience, which was December 2012, and admittedly involved a one-stop shop sort of place (i.e., the dispensary on one floor, and doc on another, and a post office down the street), was simply getting the paperwork in order (which the dispensary and doctor basically took care of) and taking it to the post office, then returning to the dispensary with a copy of the paperwork in hand, along with the proof of mailing, and buying. Then, I walked into my local (non-Denver) dispensary with my paperwork.
The Monday-Friday thing has something to do with one of the regulations regarding the time between mailing the application and getting the actual card. Technically, the dispensaries are required to be able to call on the paperwork and verify that it hasn't been denied, which can only be done during the Monday through Friday business hours of the DOR.
Nevertheless, personally, I didn't have a problem buying from those two dispensaries with my paperwork, Mondays through Fridays. Hopefully you'll have the same luck!