Camping for the Firstgrass on the 14th

Hi, I’m new to this. We have camping passes for the Mary E for the festival. Assume that from the 15th, it says that on the ticket, so what day are we able to get into the campground? Do we need to find somewhere else to stay in the 14th? Can someone help me understand this a bit better? Thx!

Saturday the 10th Mary E will open around 8am. Shuttles start running Wednesday morning.