I arrived Thursday this year and went the entire time last year so here is my take.
Yes, there will be plenty of spots open on Wednesday. You might have to wait in a line of departures when you arrive as well depending on the runway they give you. This year early Thursday I was waiting on the ground for 51 minutes trying to get into homebuilt.

Mainly because apparently warbirds getting out is the all high and mighty option to the ground crew and they stopped everything for it. If arrival traffic is light and ATC at Fisk gives you the option go for 36 L or R every time. I think 36R would be the perfect runway because it ends right at the turn that takes you to homebuilt.
Arriving midweek this year I missed virtually all of the homebuilt schedule which was kind of a bummer.
However, if the airshows are what you are mostly interested in they definitely get better later in the week.
If you plan on buying a shirt that is either small or medium that needs to be your first stop on Wednesday and hope you get lucky. Both years now I waited too long and there is usually only 12,000 XL, XXL, etc options left. lol