Member31, receiving PR through the NOVA SCOTIA DEMAND: EXPRESS ENTRY STREAM is a two-stage process. That said, I would not request PCC's or do medicals before receiving AOR from NSOI at least. Bare in mind that the expiration date of the medical will be your PR visa expiration date, and medicals are only valid for one year. Secondly, PCC's must be less than 3 months old at the time that you submit your application to CIC.
I would recommend for you to stagger the PCC's and Medicals. For some countries PCC's can take a while to process so research the average processing times for the countries that you're requesting yours from and as for the Medicals, do that closer to when you've received Nova Scotia nomination and in the pool with the 600+ points waiting for an ITA.