Scheduling downloads

If you're comfortable working in Terminal you can use the macOS softwareupdate command to download updates and run it from either cron or launchd so that it runs at a set time. I've never used softwareupdate so I don't know if it has issues, but it has been around for a while. Search for softwareupdate online and see if it could work for you.

 

I used iGetter One winter with Hughes Net. Hope I never have to use them again, but iGetter did do a good job but that was before the Mac App Store. It's free so you can try and see if they have updated it to take care of the MAS downloads.

 

iGetter is able to schedule downloads. You need to add a download from the Apple's site (i.e. Sierra Combo update, Security updates, iTunes, etc.):
http://support.apple.com/downloads/

You can find more info about iGetter scheduling here:
http://www.igetter.net/forums/showthread.php3?threadid=1216

Unfortunately, Apple don't post on their site all updates that appear in the Mac App Store, so currently you have to use MAS for the rest of the updates.

 

You may need to SysPref - App Store, and check the boxes you want accordingly (Automatically Check for Updates, and Download in background, for example)

Also, make a point to check these after OS updates - they've been known to be reset.