How to schedule download of windows 7 updates?

In Update settings, Select option Install Updates Automatically and below it there is option for scheduling the update, set it to the time which suites you.

It will automatically install updates at Specific time only without need to click to start downloading.
To stop the downloading of updates beyond the Free Hours, Use Task Scheduler to force the computer to Hibernate/Sleep/Shutdown.

Update:

You can set it to Never check for Updates and set Tasks Scheduler launch wuapp.exe located in System32, now it will not check and download updates unless you explicitly click that Update Now button, to automate this clicking of buttton use AutoHotkey, it provides a macro recorder, using it you can record a click on that specific button. It will generate a script for the click at specific position on screen, this script can also be scheduled to run that time.

Alternatively, you can turn off automatic windows updates and set them to manual. Then, create a simple batch script which runs wuauclt.exe and then add this script to the task scheduler. Schedule the task for 2 am to start the updates and then force quit at 7am even if the updates are not installed/downloaded.

open start menu, search "windows update"

open windows update and select "change settings"

there is an option for downloading at a certain time and then prompting for install later.

use this option to suit your needs