Nexus 5X Android O Release Date
As for the official release date, Google hasn't attached a specific day to the Nexus 5X Android O update's release.
During Google I/O the company confirmed an Android O release for "late summer" and the timeline points to a release sometime in Q3 if all goes well during testing.
Google was supposedly targeting an Android O release sometime during the second week of August but that didn't pan out. The company has reportedly pushed the OTA and it appears that August 21st is the company's new target date.
Google did pull the Android Nougat update out of beta in August so we could see Android O follow a similar path and touch down sometime this month.
The company recently said it couldn't guarantee Android version updates after September 2017 meaning Android O will probably be the last major upgrade for the Nexus 5X.
That said, it plans to roll out security patches to the Nexus 5X through September 2018. After that, nothing is guaranteed.