"The release of J.K. Rowling’s last outing with her creation at one minute past midnight on Saturday July 21, will be the culmination of the most fraught operation in publishing history," says The Book Standard. "Boxes have been chained shut, barbed wire has been uncoiled and satellite tracking systems for delivery vans have been double-checked," says London's Times. Book stores across the world probably haven't received their shipments of Harry Potter and the Deathly Hallows yet, but when they do their bulky cardboard boxes will likely be padlocked into secure rooms where even staff won't see them until the magical moment of release arrives.
Lest you think you can collar a bookseller the day before the big event -- or even an hour before -- to sneak off with your copy to avoid the crowds, don't even think about it. Booksellers are bound by contract to wait until just after midnight on July 21 to release to the public.
If a store breaks such a contract with a publisher, they face lawsuits and stiff fines -- possibly even blacklisting -- from the publisher! Every big release book comes with what the book industry calls its "lay down date." That's the first date the store can put the book out on public display for view or sale. That's why when you ask your favorite bookseller about an upcoming new book and they tell you it's coming out "tomorrow" and you ask if they will kindly sell it to you today, the answer is always no.
By the way, I see that Amazon.com will allow pre-order of Harry Potter and the Deathly Hallows by noon ET on July 17 for "release-date delivery". Barnes and Noble requires pre-order by July 16 for July 21st delivery in the contiguous 48 U.S. states.