It's been the better part of a year since Android 6.0 Marshmallow, or Android M, was released, and quite a while since most current Android devices across the world received over the air updates for it.

Finally this month, AT&T is rolling out Android Marshmallow to some of its top flagship devices, including the Samsung Galaxy S6, Samsung Galaxy S6 Edge, Samsung Galaxy A9, the HTC One M9, and the HTC One M8.

AT&T has been behind the rest of the pack in updating its (slightly) older devices to Android 6.0 Marshmallow, as similar models from Verizon and Sprint have been up to date for some time now.

It's understandable that AT&T is only getting around to rolling out Android 6.0.1 Marshmallow to the Samsung Galaxy A9, since the device was only released at the beginning of this year, as Android Authority noted.

But the Samsung Galaxy S6, Samsung Galaxy S6 Edge were released just over a year ago, and the same goes with the HTC One M9.

The AT&T over the air (OTA) update weighs in at about 1.5GB for the Galaxy S6 and S6 Edge, according to Android Authority, so as always, it's a good idea to have your battery more than half-charged, be on an ample, unmetered WiFi connection, and give Android M some time to run the update process.

To check to see if there's an OTA Android update ready for your device, go to "Settings," then "About Phone," and click on "System Updates" (or whatever close equivalent is on your device's menu).

Once you have Android M on your phone, you'll get features like Google Now On Tap, Doze mode, and more granular control over your apps' permissions settings.

Of course, at this point in the update cycle the next big thing from Google, Android N, is right around the corner -- offering a better Doze mode and baked in VR capability.

But considering AT&T's update schedule, you'll probably have to wait at least another year before you get that.