The macOS High Sierra download is relatively large at just over 5GB, so it may take some time to download depending on the speed of your Internet connection. When High Sierra is finally released, you’ll be able to find it linked in the sidebar of the Mac App Store homepage.
The first step to create your own bootable macOS High Sierra USB installer is to download the app-based installer Apple provides via the Mac App Store. For the current beta, users will find High Sierra in their Purchased tab after registering their Mac. Step 1: Download macOS High Sierra from the Mac App Store
