The just announced Nikon AF-S Fisheye NIKKOR 8-15mm f/3.5-4.5E ED lens is already shipping to authorized dealers in the US and should be in stock early next week (on Monday or Tuesday). When Nikon announced the lens, they did indicate in the press release that it will be available immediately. The D7500 camera also started shipping 8 days ahead of the official release date. This is a good PR move by Nikon after a series of negative news in the past few months.
Pre-order links: B&H | Adorama | Amazon | WEX | Jessops | Park Camera