This might be one of the last rumors about Apple's rumored iPhone 5S, if there's any truth to it. The new rumor is the first to come out after the announcement of the WWDC schedule, and discloses the probable availability of the upcoming iPhone.

According to an Apple Insider report, a leaked document from AU, the mobile division of Japanese carrier KDDI, shows that the preorders of the iPhone 5S will start June 20 and the device will actually be available in July.

The report also says the device will have a whopping 13-megapixel rear-facing camera and will come with Apple's upcoming mobile operating system, iOS 7.

This is not the first time rumors or leaks related to the iPhone 5S have appeared, but this leak is something special, as its timing with the announcement of the WWDC schedule is really perfect.

So far, reports, analysts and rumors were suggesting that Apple is not going to launch the iPhone 6 this year and the arrival of iPhone 5S was being suggested in every report related to Apple's mobile devices.

As Apple has not announced anything about any of the devices, it is possible that Apple will go ahead and launch the iPhone 5S at the upcoming WWDC. Rumors related to iOS 7 are also making the rounds and many suggest that the operating system will be launched during the WWDC, and this is something that gives strength to the rumors of iPhone 5S' arrival at the WWDC.

Apple is very unlikely to release a brand new device on an operating system that is already in trouble; yes, we are talking about the iOS 6.1.3. If the Cupertino-based company is going to release the iPhone 5S at the WWDC, we should also be ready to see the iOS 7.

The iPhone 5S will not be much different from its predecessor in terms of design and size. However, there will certainly be some changes inside. The iPhone 5S is expected to be powered by Apple's next A7 chip that is said to be more powerful than the A6X chip powering the fourth-generation iPad.