Frank, congratulations to you and Beth on your new unit! It's a very exciting time!
I think that Don and Mike have captured for you the two primary pieces of advice. Only six short months ago I was precisely in your shoes--picking up a brand new 2552 with absolutely no previous RV experience. The only difference is that I took delivery at the factory in Elkhart instead of a dealer, and the weather was sub-freezing with snow! I survived the experience, so you guys certainly will.
As Don says, one first order of business will be to get a little driving time behind the wheel in a non-challenging environment. You'll find that the rig is pretty easy to drive, but it will likely take a little while in light traffic before you feel comfortable with turns and lane changes. As he says, getting familiar with the larger turn radius will help you judge how much space you need to accommodate turns in service stations and parking areas. The 2552 drives and handles well, though, so it won't take long though before you feel pretty confident.
The second area that Mike highlights is to use all the systems to: 1) Get familiar with their operation, and 2) Verify that everything is working correctly or identify any problems so they can be corrected. I stayed overnight at the factory the first night, and at a local RV park the second night. I used the time to operate everything (even the A/C units and all the vent fans in 20-degree weather!). There were a couple shortfalls that first night--one because I didn't understand how the system worked, and one that was a minor problem with the unit. Both issues were corrected in short order by Phoenix the next day, and I used that second night to go through everything again to be sure everything was shipshape before I hit the long road back home. You'll get a thorough walk-through of the coach by the Camper's Inn staff I'm sure, so just focus on the operation of the systems, ask questions, and then use everything the first night, make notes if necessary, and follow back up the next day with any remaining questions and uncertainties. Both Campers Inn and Phoenix want their customers to be happy and satisfied, and they're going spend the time necessary to make sure you guys are comfortable with things before you leave. I'm sure you know that as new RV'ers, any later questions can be tossed out to the forum, and you'll find a lot of good folks ready and willing to help!
All the best, and--again--Congratulations!! Mike