We have the same unit...
A big part of your experience depends on how good the dealer is!
Our dealer discovered a BIG problem before the PDI ever happened. They had it all set up and running, and discovered an ammonia leak from the fridge. The contacted Jayco, who declined to replace the bad part, and instead just shipped a new fridge (yeah Jayco).
Schedule your PDI for early morning (to give the dealer time to address any issues right there and then). Dress in old clothes, and bring a flashlight and clipboard and pad. Plan to look under the unit, and in every crack and crevice.
A good dealer will have everything running, and will already have leak tested the roof, seams and seals, and all of the hatches and windows.
The delivery drivers are NOT always gentle! Expect loose water fittings... both high pressure PEX, and sink drain fittings. ALL of our water fittings leaked and the dealer tightened them.
Make them open the cab side windows... they are often extremely difficult to move until they have had a silicone lube put on them them. The dealer will do that.
As part of the deal we had the dealer throw in a mounted spare tire and a roadmaster tire carrier.
Roadmaster Inc. - Tow Bars, Braking Systems & RV Accessories
Our dealer had the unit ready to travel with Toilet Paper, fresh water tank filled and filter installed, basic dump hose and fittings, tee shirts, coffee mugs, insulated drink holders, 30a to 15a adapter, fresh water hose, etc. You may want to add a water pressure regulator, a black tank flush hose (never use your fresh water hose for that), a spare water filter, a clear dump hose adapter (so you can see when the black tank is completely clean), a slinky to hold up the dump hose, a 50a to 30a adapter, surge protector, etc.
We also had the dealer add a second battery, a steering stabilizer, rear trac bar, a thermostatically controlled roof vent fan, and two Coleman digital thermostats.
My wife has short legs, so we had the dealer move the drivers seat about 3 inches farther forward (there is a second set of mounting holes).
Think about what extras you need, and leave plenty of time for the PDI!!!
Be safe, and have fun!