Hit your store at 3: -- I'd be surprised if you are not able to walk away with one of some flavor.
It depends on the store and how many copies each store gets. I would not want to wait until the last minute to get there. Someone who waited too long for a pre-order could find it hard to get to the line they need by 3:00 and lose out. Can you imagine trying to get to the reserve line in time and finding a crowd that would stop you for chance at your unit? Nothing criminal, just not letting anyone cross through where they are at. Knowing if they run out of in-stock units, Apple will take reservations for the few unclaimed units. Some stores may have very little store traffic, but others may be impossible to navigate.
at the best buy store in ft lauderdale tonight (apple section), they advised they would have units for sale on saturday, april 3rd
As early as possible, apple is a huge company and a new product will get sold out very fast in stores.
Also told to bring "proof" of reserved iPad paperwork to expedite any confusion when the 3pm line frenzy begins.
Happy hunting to us all (grin)