+1 - Big races fill fast. It doesn't take long to search on bikereg for events. In the Chicago area there are a ton of local websites that have event calendars that directly link to the bikereg page. Bikereg lists the reg open time explicitly at the top of the reg page.

Most of the early season big events for this area fill quickly in the 5's and even 4'3 and 3's. It's a PITA to have to register while at work and I would appreciate if they opened reg at 7pm or so, but I would probably lose out on more events that way as the lazy sleeping in college students would probably be awake at that point and not starting threads on BF about how they can't seem to use a computer to register for an event at the ungodly hour of 8.