“As part of final preparations for the general availability of the Windows 10 Fall Creators Update on Oct. 17th, we have begun releasing Build 16299.15 to Windows Insiders in the Release Preview ring. If you are in the Release Preview ring and don’t see this build offered yet – be patient as it will be rolling out over the course of the next few days to everyone in the Release Preview ring,” said Microsoft’s Dona Sarkar in a blog post.If you participate in the Release Preview ring, you can grab build 16299.15 from Windows Update to test the new version of Windows 10.
Regular Windows 10 users will need to wait at least one more week. Keep in mind that Microsoft rolls out these updates in waves. They want to avoid compatibility issues so it can sometimes take several weeks or months before this update reaches your system. But if you want it faster, you can always force a manual install.