Step 9: Get Familiar with OTA Process & Sideloading
Google's Android releases can be extremely slow and unpredictable. In its Android Marshmallow update, the company alludes to this when it says that the "Nexus update to Android 6.0 Marshmallow occurs in stages and some carriers will receive the update later than others." In other words, it could be awhile before you see your OTA.
Fortunately, these are Nexus devices and that means that you can install software early provided you have some basic knowledge about sideloading and bootloaders.
This guide on how to install the update should get you up to speed though there are plenty of other resources out there that will help you learn about manually installing software ahead of an OTA.
If you’re not comfortable after doing your research, you should wait for the Nexus Android Marshmallow OTA from Google to arrive. Manually installing software can cause problems so you'll want to feel very confident before making the move.