Google testing a feature that prevents an app from downloading over a cellular network?
Please select 1 - 3 phones
Since it is being tested right now, some Android users might see this option on their screen while downloading an app. If you do get the option to choose between downloading a file now or waiting for Wi-Fi, selecting the latter will automatically start the downloading process shortly after you're connected to a Wi-Fi network, You won't have to click on anything to start the download.
Those who have tested the feature say that it is a little buggy for now. But Google will surely work hard on having the bugs fixed by the time this so called 'queue-for-WiFi downloading' is ready to be launched. And if you're the type that loves to download apps, you might find that this will save you a decent chunk of data every month.
source: AndroidAuthority
Things that are NOT allowed: