The 30-day free access that you should get from your full registration code will start on the day you enter the full registration code to PSN and log in to your SE account and apply it to the FFXIV Service account. (Getting it applied to the service account is something for which you will be prompted to do the first time you log into your SE account from the PS4 after you enter the code to PSN.)

You may miss some play time if the physical delivery of the product does not happen until Wednesday or later, but you will still get the 30 days once it does show up. Your early access time does not count on the 30 days.