léonie thank you for your suggestion.
I clearly could that - but to use my overnight bandwidth I'll need to remember to check downloads between 11pm and 7am - and I'm not always around - or going to remember - to do that.
Some bandwidth smart apps (e.g. Crashplan cloud backup or uTorrent download apps) are aware that they use precious bandwidth and they give options to restrict their use of bandwidth to certain times or days.
It's a solution along those lines that I'm seeking - so I can continue to have Mac App Store apps download in the background - and be ready for use when I'm at my Mac - but for the bandwidth hungry downloads to happen overnight.
You can only do that individually every day, I am afraid.
The AppStore offers some control from the "Updates" panel: (from the "Help")
Click the disclosure triangle next to Update All, then choose an option:
If you choose to install updates tonight, they are installed between 2:00 and 5:00 a.m. If you install updates that require you to restart your Mac in an hour or tonight, a notification appears prior to updating, which allows you to delay the update.
You could try the option: "Try Tonight".
But with the option “Download newly available updates in the background” enabled, the updates will be downloaded immediately and only installed later, so you cannot have this option active, if you want to prevent downloads during the the day.