The current night light assumes a normal day time schedule (fair enough) and can only be set to change with the sunset (I don’t believe you can say set it for 6pm, or 7pm daily, it changes with the time the sun naturally sets, at least I can’t find a way to set it statically), be always on, or be always off. While the ‘Suspend night light’ feature exists to temporarily turn it off, there isn’t a way to have it globally disabled by default during the day, and be able to quickly turn it on when the natural day colors shift. I feel like this change would benefit most people, as instead of booting their machine and immediately having to turn off the night light, they can have normal colors and brightness at boot and turn on the night light when it’s later in the day. I use the night light daily, I work a 3rd shift job and when getting home at 5am I like it to be darker, but I can also understand the opposite, using the computer mostly during the day and if you want the night light at all you have to turn it on entirely, or at the very least at sunrise and sunset, so it’s sometimes not worth going back and forth to the settings page, and instead just leaving the night light on and manually disabling it every time you start your computer.
The times for sunrise and sunset can be set under “Language & Time” → “Day-Night Cycle”. That being said, I actually misuse the suspend option since it exists: By default the night light is suspended and I only un-suspend it when necessary. The lighting conditions can simply be bad at times due to bad weather, automatic shutters etc., so at least for me this day-time scheduling for the night light never worked.