As far as I know, 8 am is never a regular opening time; it's only an EMH opening time, except for really busy times like Christmas, Easter and spring break. And according to your ticker, you're going in early June, so it's not an issue.
They do some 8 am openings during party seasons when it looks like the crowds are going to justify it. We were there in mid-December, and there were 8 a.m. openings, but the crowds were no where near Christmas levels. Frankly, it was fabulous. No one was there that early. On our last day in the parks, we walked on BTMRR four times and Splash twice before 9 a.m. On prior trips, we had a couple of 8 a.m. openings during October as well. When Disney does this, it doesn't seem to be well-advertised and the crowds are still practically non-existent until about 11:00.