Hook, IF I remember correctly from last year, we went in about noon, and some of the stages had performances going on, the smaller ones. They each played about 30-60 minutes each. Downtimes were real quick.
The Mane stages started a bit later, but those sets were also longer, the later it got. Headliners played for about an hour.
Thought you would like a bit more info from experience.
We would head in about 11 in the am, people were marking their spots, and some music on some stages were starting by noon...it continued until midnight as noted.
So relax in the am, have brunch, head into the grounds, grab a spot, or cruise the vendors, food, bbq contest, check out the different stages. We cruised all over...blisters were HUGE! You will be back to your rig about midnight.
WE also noticed that the only bar with top shelf vodka ie: Kettle One, was the furthest stage under the tent, that was a bumber...but that was a fun tent, dance floor and all!