Sales of the 1936 Norfolk, Virginia Bicentennial / Tricentennial Half Dollar began in September 1937 - in-person sales and mail order fulfillment were each initiated on the day the coins arrived from the US Mint. (Monday, September 13, 1937)
The Norfolk Advertising Board, the coin's sponsor, stated, at the time, that approximately 10,000 coin orders had been received via the mail. Coins were available locally via in-person sales as well as by mail.
In what smacks of being a staged, made-for-the-media event, Carolyn Holder, a nine-year-old girl, was the first person to purchase one of the new coins after waiting for Francis E. Turin, head of the Norfolk Advertising Board, to arrive with a Mint bag of the Norfolk half dollars. It was a "photo op" fully exploited by the local press.
Behind the scenes, the coin order of Helen Brown of Long Island, NY was the first to be filled by mail. It was reported that she had been waiting a year for the coin. (Quite a pre-order!)
By early 1938, the Norfolk Advertising Board was winding down its coin operations and alerted collectors of such with an advertisement placed in the February 1938 issue of the
The Numismatist magazine, the official publication of the American Numismatic Association. Coin sales continued into the Spring, with some bulk orders sold to dealers at discounted prices.
1936 Norfolk, VA Bicentennial / Tricentennial Half Dollar "Last Call" Advertisement
(Image Credit: American Numismatic Association, The Numismatist, February 1928.)Ultimately, 16,923 coins were sold of the 25,000 struck and delivered (+ 13 Assay coins), with ~8,000 returned to the Mint to be melted.
1936 Norfolk, VA Bicentennial / Tricentennial Half Dollar

For other of my topics on commemorative coins and medals, including more on the Roanoke half dollar, see:
Commems Collection.