There was a huge lag for the last OTA (Over The Air) update for N7 2012 WiFi. The 4.4.4 one will hopefully come quicker. Word on the street is that it is a small update to close a security vulnerability from 4.4.3 - so you (and everybody else) will want to get updated.
There should be an OTA update pushed out by Google that you can get via WiFi. If it comes in you will get a notification that your device is ready to update. To check manually if it is ready: make sure you have a data connection and got to Settings > About tablet > System updates and press the button that says Check Now. An OTA update will not wipe your data.
Your bootloader is still unlocked yes? That's fine if it is. It won't affect getting an OTA. However, if you have root access, custom recovery, a custom kernel or Xposed Framework any/all of them need to be removed/returned to stock before an OTA update will install itself...