Good luck with that. Heard good things so you should have fun with it. After all these years I'm considering getting a PP; the GPX 11" coil is a beast on the deep stuff but still makes me dig broader holes than what I prefer to get the coil in for better discrim - REALLY deep big iron down around 2" won't discrim with this monster until you get closer. Stuff in the side walls sounds like its straight down at times due to the amount of aura being detected, so how to broaden the hole which I don't like.
Check out youtube for ways to GB your PP, as well as determining how close you are to the relic. I saw one vid a guy made where he used his PP to determine where the relic was, then did something on the side (can't remember what now but he explained it well and easy to understand), and put the PP back in the hole. This time there was no signal whatsover telling him it was deeper than just below the surface. As he dug closer the PP started to sound off again letting him know it was close and to slow down the dig to avoid any damage. Neat trick to give you an idea of the depth once you've PPd a relic.