Microsoft has yet to commit to a release date, but if its name is any indication -- Windows 10 October 2018 Update -- then we can expect the next major update to Windows to hit next month. It will introduce a number of new features, including SwiftKey keyboard for touchscreen PCs, a better screenshot tool, the Your Phone app for iPhone- and Android device-wielding PC users and a less annoying approach to restarting your PC to install incremental updates.
If you're eager to get going with Windows 10 October 2018 Update, then you can install a prerelease version right now. Microsoft is in the late stages of development for the update. The preview build I've been using has been stable, and I expect it to be fairly close to what we'll see in the final version in October. Microsoft has been developing this next version of Windows under the name Redstone 5. The official version number of Windows 10 October 2018 Update is version 1809. (The current version of Windows is Windows 10 April 2018 Update or version 1803.)
Before we get moving, allow me a word of caution.
Back up before upgrading
Before you install any big OS update, it's a good idea to back up your system in case something goes awry during the installation. You can simply upload important files to your preferred cloud service or an external drive. Windows' built-in backup service can be found by going to Settings > Update & Security > Backup.
How to install Windows 10 October 2018 Update early
To download and install a preview version of Windows, you need to join the Windows Insider Program. Don't worry, it's free and easy to join. An exclusive club, the Insider Program is not.
Open Settings and click Update & Security.
Click Windows Insider Program on the left column and click the Get started button.
Click Link an account, select your Microsoft account and click Continue.
For the question, "What kind of content would you like to receive?" your answer will be Active development of Windows.
For the question, "What pace do you want to get new builds [at]?" your answer will be Fast if you want them fast and are willing to put up with the occasional bug or Slow if you don't need to be the first in line for each new preview build and want to install updates after more of the preview bugs have been fixed.
To finish, click Restart Now to restart your PC and begin installing Windows 10 version 1809, aka October 2018 Update, aka Restone 5, aka rs5_release. At the time of this writing, I'm using Windows 10 Insider Preview 17754.1.
To check if the update has started installing on your PC, head to Settings > Update & Security > Windows Update and see if Windows 10, version 1809 is installing. If not, click the Check for Updates button, which should begin installing it.
Opt out of previews after official release
After the official version of Windows 10 October 2018 Upgrade is out, you can opt out of the Insider Program by going to Settings > Update & Security > Windows Insider Program and clicking the Stop Insider Preview builds button.