In Fable and The Lost Chapters, the only way to know the best time to sacrifice is to look at your alignment bar in your menu. There are 6 bars on each side, and neutral in the middle. Each bar should be translated as 1 hour of night. If you are completely good, your sacrifices must take place just after sunset, and if you are completely evil, your sacrifices must take place just before sunrise. It is a common misinterpretation that the optimum time for sacrifice is at exactly midnight, but this is most likely because the people who did it had a neutral alignment.
In Fable II, the ideal time to make sacrifices, at the Temple of Shadows, is between 12 Midnight and 1 A.M.
In Fable III, it does not matter what time you sacrifice at the Dark Sanctum.