Windows Insiders have a short period of time around the release of each Windows 10 version to opt out of preview builds and get back on the normal release schedule. But here’s a heads-up: The time period, which I call the “magic window,” is about to close for the Fall Creators Update.

As a reminder, those who opt a PC into the Windows 10 Insider Preview are pretty much “stuck” on the pre-release Fast or Slow ring: They can slow things down or speed them up, but they can’t get off the train. Without reseting the PC, of course.

But when any Windows 10 version is completed, as the Fall Creators Update (also known as Redstone 3, or RS3) was recently, there is a short “magic window” during which you can opt out of the Insider Preview without any repercussions. That is, because the build of Windows 10 you’re using—in this case, 16299.15 for both the Fast and Slow rings—matches the initial shipping version of the Fall Creators Update, you can simply leave the program. Nothing bad will happen, and you will just continue getting the normal quality updates like everyone else going forward.

If you don’t opt out of the Windows Insider Program, that PC will be switched over to the next version of Windows 10 after the Fall Creators Update, called Redstone 4. And that switchover, which closes the magic window, could happen as soon as tomorrow (Tuesday, October 10). So you need to decide quickly.

To exit a Fast or Slow ring PC from the Insider Preview and get back on the normal update schedule for Windows 10, open Settings and navigate to Update & security > Windows Insider Program.

Here, select the “Stop Insider Preview builds” button. When you do, the following pop-up appears.

Select “Stop Insider builds completely” at the bottom. Then, confirm your decision and reboot as instructed.

You’re out!

Thanks to Richard Hay at the SuperSite for Windows for reminding me about this crucial milestone today on Twitter.