Good news for Pixel and Nexus owners; Google's January factory images are now available for you to load up. This is the first security update since Android Oreo 8.1 rolled out last month that brought over some newer features to older Pixel devices, but also enhanced burn-in protection on the Pixel 2 and squashed some bugs.
The update fixes dozens of security issues, so you'll definitely want to accept the update as soon as you can.
If you own a device that's slated for the update, you should see the OTA update fairly soon. If you want to sideload the update without waiting you can grab those files at Google's link below, but you might not want to take that route this time. There have been a few reports of lag after sideloading the update instead of waiting on the OTA update, so unless you're comfortable with a potentially late night of resetting and fixing your phone, you might want to exercise some patience this time.
source: Google
got it OTA last night on my Pixel 2 XL, no lag so far