Once these calculations done...

you'll know how much time you have, in daytime and night-time, and the time schedule for your ritual.
This is very important because you have make sure you end your ritual within the time frame and chooses the time frames in which you are the most likely to be alone without anybody bothering you.

An example:

going back to the calculations of 8 May 2001, perhaps you prefer to do the ritual in daytime, as the unequal hours are longer then, and start your ceremony in 4:43 AM before going to work in the morning.