I am getting my ED delivery in May so I have some info on this. You can reserve your ED spot at the dealer now but pricing is not available yet because any deliveries after 4/15 are MY2011 with LCI changes. The ED pre-reservation form will ask you to pick 3 dates for delivery. However the car cannot be ordered until March or April according to my ED specialist. Hope this helps.
On a side note I thought the Welt is opened Mon-Sat, but no factory tour on the Sat.