You can’t find the “From Sunset to Sunrise” setting in the schedule options of the Blue Light Reduction settings introduced in iOS 9.3.
Settings -> Privacy -> Location Services -> System Services and turn on Setting Time Zone.
Apple needs to access you location to determine the sunset and sunrise of your current location. It seems like Apple choose to bind the
Setting Time Zone option to the Night Shift feature. This is the reason why the sunset to sunrise option doesn’t show up for people who have unchecked the Setting Time Zone option.