I had also thought it's ridiculous. my appointment
was 8am, same as u, and the ASC is 150 miles away from where i live.
When the day came, I woke up at 4:30 am, started off at 5am, and arrived at the ASC before it opened.
so, i believe u'll make it. :)
however, I DO NOT think it's very critical u must show up at 8am.