Welcome to the forum!
Search for a thorough RV PDI, pre delivery inspection checklist, here and/or across the web. There's a good one in Ed Felker's manual, see the sticky.
Check and test everything, every appliance, door, drawer, and switch and shade. Test everything that uses power on AC, battery and generator. This will take HOURS, don't let yourself be rushed!
Here's to many happy miles and adventures!
If all else fails, read the directions!!