Void of Course

Lately I have been trying to learn about and employ cord magic and astrological alignments in my spellcraft largely due to a very interesting discussion posted by Lark on cord and knot magic. I have eagerly awaited the waxing moon as there are a few serious things we need in our lives right now that I intend to do workings for. I thought I had figured out the perfect days to cast these spells, using the moon phase and the zodiac house in which it sat at the time. Then I came upon the "void of course" concept. Apparently, the moon is considered void of course when it has completed its last planetary aspect in one sign and begins to move into another. There is some debate as to when this phase begins and ends, and it seems to be considered a bad time to cast any sort of magic as the energies of the moon are confused at this point. So in order to be safe, I suppose it would be better to avoid casting on void of course days altogether. Does anyone else know anything about this concept and do you avoid casting at these times? Can anyone explain this phase to me and exactly when casting should be avoided? I have searched this site and found nothing on this subject. Any information or help would be greatly appreciated. :)