Welcome to the forum. Yep... I had my share of butterflies when I got my 40DP... but soon, that'll turn to excitement as you'll look forward to hearing that big diesel come to life when you turn the key.
There really isn't an answer to your leveling question because it will vary from rig to rig... and often times, not only is a site sloped from back to front but also side to side. This might cause a jack on one side not to have enough reach while the other side might be fine.
It's a trial and error thing with a big DP. Carry some wooden pads to stack under your jack(s) when necessary to give you that extra couple of inches.