Do your updates on your device, controller and bird. Once they are all up to date, do your calibrations. Necessary? Maybe not but it never hurts. Checking the settings on your device is a must. The RTH height and camera settings are just a couple that come to mind, but check everything.
The batteries may or may not need to be updated. Depends on how long they have been on the shelf. I bet they will however. This will be done when you power up the bird and the firmware will do the update automatically. I would try to do all of this before you head for the field to fly. It could take some time.
Top off your batteries if you want but do some research on battery care. Some take the 50% approach for the first x amount of cycles and some don't - but now, when new is the time to decide what is best for you.
Finally, make sure you do a compass calibration at the location you fly, before you fly.
Welcome and enjoy your P3S.