No that's how it works. IIRC they let the sites go in 2 week blocks 5 months in advance. You must be online, on the reservation site with the specific site that you want active. At 8 AM PST, actually maybe 2 minutes early, you need to start clicking the button to reserve that site. It doesn't hurt to have two sites open in different tabs, if you lose one, tab to the second one. Also having someone else in the family doing the same on a different computer for a different site might make sense. The two minutes early idea is that you do not know if your clock is synchronized with the website.
I got my first choice when I did it. But all the available sites go within minutes. They check ID cards when you show up so reservations cannot be passed on to someone else.