You asked when to leave in the morning.  As others have answered, it’s up to you; however, if you go with a charter or have your bags hauled by the Rag semi’s, there is a specified time that bags have to be on the trucks, so you must be up, packed, and loaded by that time.  I guess you could lounge around for a while, but most people leave after loading their bags.  Some much earlier!! 
Also, unless you have an RV, or can (doubtful) set up your tent away from the masses, you’ll start hearing tent zippers/talking/kybo doors slamming before sunup, so it’s kind of hard to sleep in.
Other than that, as mentioned, the beauty of Ragbrai is few hard decisions, just do it as you want.  You’ll never be alone on the road, guaranteed!