Xuankong Dagua is a branch of Feng Shui. It combines time, location, personnel (year of birth) with 64 hexagrams to see whether the combination between these hexagrams is good or bad, for example, whether there is a relationship between hexagrams and hexagrams. Transportation etc. It can be a method of choosing a feng shui auspicious place, or it can be a method of choosing a day.
As for how to choose the time, it is very complicated and difficult to explain one by one, because it takes a long time to study even if you teach. For example, now is the Eighth Luck, and the Eighth Luck takes Gen (of Bagua) as the main god, then the Chou Gen Yin (in the 24th Mountain) is preferable, then look for the Chou or Yin day in the Chou month or Yin month to see the noble person on that day ( What is the evil spirit), and then choose the hour of the noble person. The selection method for Wutu solar or lunar time is similar, but the formula for determining the time is different.