The Google Nexus 6P will start receiving the latest Android security patch next week.
As listed on Vodafone's website, March security patch for the Nexus 6P will begin rolling out from March 7. There's no information regarding the release date of this month's security patch for the Nexus 5X, However, it is likely to get the new update along with the Nexus 6P.
The update will carry a build no of N4F26T, and will come with "5 March 2017" Security patch level. It will be available via FOTA and will cost approximately 39MB.
Last week, Google announced Android 7.1.2 Nougat Beta for the Pixel and Nexus devices. So, those who are running Android 7.1.2 Beta will not be able to receive March security patch update via OTA.