Exact Time Beta will be avaliable

i cant seem to find this question's answer anywhere (that has a specific answer) so im sorry if it is somewhwere out there.

When is the exact time the beta will be avaliable?

From 5:00 A.M. PDT on May 16 through 11:59 P.M. PDT on June 6, CrackdownTM owners and a few other lucky Halo® fans will get a sneak peek at this year's most anticipated game by participating in the Halo 3 multiplayer beta test on Xbox LIVE®.

http://www.xbox.com/en-US/games/h/halo3/20070511-mulitplayerbeta.htm?WText.camp=HR1-Halo3Beta&WText.campSrc=Home