From Apple’s press release:

Apple® today announced iPhone® 6s and iPhone 6s Plus, the most advanced iPhones ever, will be available at 8:00 a.m. local time on Friday, September 25 at Apple’s retail stores. Stores will have the new iPhones available for walk-in customers who are encouraged to arrive early. Both models will also be available on Friday from AT&T, Sprint, T-Mobile, Verizon Wireless, additional carriers and select Apple Authorized Resellers. Apple also announced the fastest iOS adoption ever, with more than 50 percent of devices already using iOS 9.

Amazing to me that iOS 9 adoption is already at more than 50%. And that was as of Friday. Remember, the launch was Wednesday.