How to keep Night Shift™ enabled indefinitely on macOS 10.12.5+? Settings only have "turn on until tomorrow" I want to keep it turned on until I turn it off, not until some fixed date. How to achieve this?

(I know about the option to use f.lux, but I'd prefer to not depend on it now that macOS is so close to being able to do it itself)
In the preferences (System Preferences > Display > Night Shift) do the following:


set 'Schedule' to Custom
set 'From:' to 00:00
set 'to:' to 23:59
adjust the Color Temperature as desired


Now night shift will be enabled all the time. Disable it using the Notification Center or using the 'Manual' toggle in the preferences pane.