Nexus 6P beta testers are being updated to the stable build of Android 7.1.2 Nougat, a variation of the software which users with the Nexus 6P technically already have, but in beta format. While it might still take some time for all Nexus 6P owners that were using the beta versions of the 7.1.2 software to receive the actual update, it appears that users are starting to see alerts for the updated software that will bump them from beta status to a stable build of the software which means that it's possible all users could have the stable build within a week or so.
Since this is essentially the same version of software that users were already on the update file shouldn't be too large of a download. The image below shows it coming at just 25.4MB which is pretty small and that should take almost no time to download and complete the installation. You will of course need to have a decent amount of battery life left or the system won't even allow you to initiate the update process, so it's a good idea to have at least half the battery life on your device if you want to follow through with the update.
Right now only the Nexus 6P beta testers on Android 7.1.2 Nougat are receiving the update to the stable version of the software so anyone else on the beta with a different device will still have to wait a little bit longer it looks like before they get the same treatment. There is unfortunately no indication on how long of a wait that might be, but the good news is that users aren't really missing out on much since there no differences in regards to features. What the stable build does do though is allow you to receive future OTA updates for stable software, so this is something you'll want to install if you don't want to rely on always flashing software to your device manually when new compatible software is made available. If you haven't seen the update alert show up in your status bar you can always check manually to see if the update is available by going into settings, then about phone, and tapping on the software updates option. Alternatively you can download the file manually from the button below and flash it yourself if you wish but it's only compatible with the Nexus 6P.