Congrats and good luck with your new 26DBH. I've heard Dealers short cutting the prep work for delivery is often why many trailers need to return for warranty work during the first year. My advice is to get there early to start the walk-thru and do not rush thru it, take the time to use everything so you have a good understanding of how it all works. And beyond just how things work keep on eye out for any loose screws, water hose fittings (i.e. leaking), all drawers open/close properly, and so on.
Since you had the 2280BH you have a good idea. Consider creating a detailed checklist beforehand. Your first trips out will go much smoother if you know all about the important stuff like the slides, converter, disconnects, water heater, etc. but also the minor stuff like using the TV (antenna vs. cable) or adjusting the stereo volume. Doing a thorough walk-thru may save you from having to bring it back anytime soon.