I've seen Acceptance Day as August 7 on 2 different "official" pages (webguy being one) so it appears that is the date. Its slightly different timing than the previous few years (was the day before classes started, now there is a day in between).
The Acceptance Day parade begins at 9 am, so you'll definitely need to fly in the day before. I took time that day to shop for some things for my cadet (snacks, printer, a few other things he needed--they get their computers a couple days before the parade so we e-mailed). The parade lasted about an hour and a half, then comes the shoulder board ceremony (each squadron handles their own) which parents can watch. Then every squadron seemed to have a picnic, food provided by the parents attending. Some cadets and parents will choose to eat at Mitch's (dining hall), go to the book store, etc. After my son and I left his squadron picnic, we carried the stuff I brought up to his room. Generally, parents/visitors were told they could stay until about 1 pm, although some were there a bit later than that. My son's squadron had a briefing to attend at 1:30, so I did scoot out of there around 1 and flew home that evening.
In my son's squadron, I'd say about half of the new cadets had parents/family members attend. It is a very short visit, but also very moving to see them accepted in to the wing, so worthwhile I thought.