When will you people get it into your heads that the staggered launch is NOT for server load, they already tested that with the beta weekend and it was fine. The staggered launch is for zone population reasons. Instead of having everyone be in the same place at the same time killing the same mobs (or rather waiting for respawn of said mob) they let some people in earlier so they won't bother you when you play and you won't bother the people after you.

where are those numbers from?

They're not staggering for the server load, but for the zone population. If they'd let in all at once the starting zones would be way overcrowded, especially since there's only 2 of them. If they stagger the access, many people will have gotten past it and many will not be able to get in yet when you are playing.