Apple Insider
Apple might be able to update your iPhone even if they're still in their packaging and Apple's stores. Typically, when you buy new hardware, you would need to update the device when you first open it. But Bloomberg's Mark Gurman reports in his newsletter that Apple has a system that can update the iPhone's operating system before they get sold. And they don't even have to be taken out of the box.
There will be a "pad-like device" in stores where employees can place unopened iPhone boxes to trigger an update. This pad will wirelessly turn on the iPhone, run the software update, and then turn it off again. This system might be in place before the year ends.