As you can see in the screenshot above, it was taken from Apple’s macOS website in which at the top of the page, it says “Available 9.20” which basically means macOS Sierra will be available for users on the 20th of September. This is much earlier than we had anticipated given that it’s almost a month earlier than the rumored dates, but that’s not a bad thing!
Given that Apple plans to release their other operating systems like iOS 10 and watchOS 3 on the 13th of September, it would make sense for macOS Sierra’s release to not be too far behind. As usual macOS Sierra will be a free upgrade for users on Mac computers, so if you want to get your hands on the latest features you’ll want to upgrade when it is made available.
We still don’t know when Apple plans to announce the new MacBook Pros, but presumably we will see the refresh towards the end of the year which Apple tends to reserve for iPad and Mac-related announcements.