Camping opens @ 6pm on Thursday, it takes awhile for people to get in so I can't imagine that 9pm would be an issue. However, we got there at 5pm last year and there was already a sizeable line.
My goal is to leave Hartford shortly after 3:00 on Thursday afternoon. Last year we managed to grab about 3 contiguous 10x20 spots which is enough for 5 4 person tents and a small area to hang out around a stove/campfire. However, that was with Will and Gary and one of my friends arriving before the gates open, so ideally we'd need 2 more cars to get the same type of space (or better) this year.
As a side note I have an interview on that Friday so I will be leaving around 9am and will be back around 2 or 3 if anyone who is planning on camping Thursday thinks they might need a few things (generally ice) on Friday afternoon.
Also, unless I missed a post I do not believe anyone is bringing a grill/stove/firepit yet. My firepit was sacrificed to the limerock gods last year so I no longer have one and we usually rely on Will for the grill but he is iffy on coming.