Oshkosh: which day?

I am trying to pick a day to visit Oshkosh. My plan is to fly up in
the morning and return that evening.

I've been to Oshkosh many times but never flown in. I have read the
NOTAMs and understand the arrival procedures, but need some help with
logistics questions.

I understand the field is closed at 8pm. How early should I head back
to the plane to make sure I get out by 8pm? I assume 8pm is a 'hard
stop'. Ie last aircraft departs at 7:59:59.

How long is the wait for VFR departures? If the weather is bad, how
long is the wait for IFR departures?

Since I am in/out for the day, should I still request 'GAP' parking?
Or is there a 'transient' parking area?

What day is best for this type of in/out flight. I'm thinking Sat/Sun
are bad choices due to the increased traffic. I am mostly interested
in looking at the static GA, homebuilts, and warbirds, plus a few
vendor tents. Not really interested in the airshow portion.

Thanks,
Nathan