Those who managed to get updated to Android 4.1.2 before the process was halted, will still receive the update. This will keep the device at Android 4.1.2, but will add new security features. Those whose LG Optimus L9 is still running Android 4.0.4 will finally get the Android 4.1.2 OS build which brings Project Butter for smooth scrolling, Google Now for information you need when you need it, and time saving actionable notifications.
The only way for owners of the phone to snare the update is through the OTA download. The update started getting sent out on Wednesday and is being sent out in waves which means that if you haven't received it yet, you will soon. If you can't wait for the OTA download, you can try to pull the update out by going to the home screen and clicking on Menu > Settings > About device > System update. From there, follow the prompts.
source: T-Mobile via AndroidCentral