Apple is gearing up for its first major hardware and software launches of 2014. The Cupertino-based company is “tentatively” planning a keynote address in mid-September to announce the iPhone 6 and provide final details on iOS 8, according to sources briefed on the plans.

These people say that the second and third weeks of September are the mostly likely weeks for the event to be held, but they add that manufacturing uncertainties could alter the event’s timeframe. A decision has not been finalized, and sources made it clear that the plans are in flux.

The event will showcase at least the new iPhone 6 with a 4.7-inch screen, the sources say, but a final decision on debuting the larger, 5.5-inch “phablet” model at the event has not been made. The 4.7-inch variant of the new phone is farther along in both internal testing and manufacturing preparation, the sources added.

The iPhone 6 will be a significant launch for Apple with its bigger display and slimmer design. Yesterday, Apple announced that it has sold 35.2 million iPhones in the June quarter. While that number brings iPhone sales up roughly 12% year-over-year, the sales figure came in below the expectation of financial analysts. Apple CFO Luca Maestri said iPhone sales were on the high end of Apple’s own expectations, but he noted, as Apple does annually, that sales could have been higher if it were not for “new product rumors.”

As Apple sets its sights on unveiling the new iPhone hardware, the company is also racing to finish up iOS 8, the software that will come pre-loaded on the iPhone 6. Apple is nearing completion of iOS 8.0’s development, and it plans to release a fifth and likely final beta to developers for testing on Monday, August 4th, according to the sources. Apple will finish up work on this beta 5 early next week, the sources said, and a golden master version of iOS 8 will be completed either in late-August or early September in order to provide ample time for both carrier testing and the installation of the iOS onto iPhone 6s in production.

As iOS 8.0 with improved messaging and a new Health app nears a public release, Apple will soon turn its iOS development attention to iOS 8.1 and iOS 9. Apple has been working on a new dual-screen multitasking mode for iPads as well as new functionality for Maps that should be ready for either 8.1 or 9.0. Apple originally planned to debut both of those features in the iOS 8 version launching this fall, but engineering resource constraints as well as internal politics have caused internal delays.

Apple is said to also be planning a second event for the fall that will take place in October. As others have reported, this event will likely center around Apple’s upcoming wearable fitness band. Besides the wearable device, as we reported yesterday, Apple will utilize October to talk about the upcoming OS X Yosemite.

Also in Apple’s pipeline for this fall are new versions of the iPad. Sources and previous reports say to expect a more modest series of iPad updates this fall that center around internal device improvements and Touch ID fingerprint scanners. As he says almost quarterly, Cook said yesterday that “significant innovation” is in the cards for the iPad in the future.