Tap “Manual” if you want to turn it on or off manually.
When Do Not Disturb is enabled, calls and alerts that arrive while locked will be silenced, and moon icon will appear in the status bar.

Check out moon icon when Do Not Disturb is enabled 

Tap “Scheduled” if you want to set a certain time for Do Not Disturb feature
Tap  the time from, to, to set the time

Set the From time and To time as you wish

Tap “Allow Calls From” if you want to make some exceptions
The default is set as Favorite which means it will accept the calls from your favorite contacts even though this feature is on

Change as you wish. It will allow calls from either ” Everyone”, “No One”, or “Favorites”
Well done