Yes, dark/light is determined by sunset/sunrise setting in your M1.. Dark/Light is a qualifier used after an AND. You can always adjust for a certain time period Before or After using the rules. In this case you would simply use the sunrise/sunset rule instead of simply light or dark. So, in your case if you wanted to do something 30 minutes before sunset, instead of saying
WHENEVER event AND IT IS DARK OUTSIDE
you would use
WHENEVER event AND THE TIME IS 30 MINUTES BEFORE SUNSET
Does that make sense?