The much-awaited iPhone 6s release date is rumored to be arriving earlier than its expected September release date. Sources also say it will have great changes mostly due to an impending iOS upgrade.

Forbes said that there could be a possibility for Apple to release the iPhone 6S in July even though the iPhone 6 and iPhone 6 Plus are still selling well in the market.

Analyst Ming-Chi Kuo expects the device to be available this coming fall, ahead of its rumored third or fourth quarter release, according to ValueWalk. This would be a surprising move for Apple since the Cupertino-based tech giant usually follow its schedule of releases during the fourth quarter of the year.

Kuo predicted that the iPhone 6s will not have an increased size once it is released.

"Kuo believes that Apple will stick to 4.7-inch and 5.5-inch displays, with a roughly 2:1 ratio between the two devices in terms of units available," added Value Walk.

As for its iOS, Forbes has learned that Apple may be planning on putting iOS 9 to the iPhone 6s out of the box—something that is set to be confirmed during the Worldwide Developers Conference (WWDC) this summer.

A separate Forbes report added that the coming iOS 9 will have a new app called "Home."

"Home will begin a major Apple push into the so-called 'Internet of Things' (IoT) and act as a control hub for third party HomeKit products, much like the roles of Game Center for games and Health for Healthkit apps," explained Forbes.

Interestingly, the iPhone 6s is also rumored to have a major change in appearance with an "eye pleasing new look." Then there is also the major change in font from the skinny Helvetica Neue, which came with the iOS 7, to "San Francisco."

The most important aspect of the iOS 9 is said to be its ability to perform complex multitasking, which is going to be very evident in the upcoming iPhone 6s.

9to5Mac has learned that iOS 9 will also have a "redesigned Siri application," one that is very similar to the colourful user interface of Siri found on the Apple Watch.

"We're also told that the new release has a default wallpaper made up of a blue and green color scheme. Apple has also been working overtime on major security improvements. We'll have more details on Apple's plans for WWDC, including more details on the new Apple TV, Web TV service, and OS X 10.11 'Gala,' as the conference approaches," added 9to5Mac.

Once available in the market, PC Advisor said it may have the same price tag as the iPhone 6 which is around $835.  

All these announcements for the upcoming release make iPhone fans more and more excited for the iPhone 66.