Whoa; this sounds bad. Further information on the virus can be found on a Microsoft Security Advisory. This could be a very potent attack, although the time delay is rather odd. Why make that big of a time gap between a large number of people receiving the worm and the worm's attack? It would seem smarter to have it attack every day, not just the third day of each month. I wouldn't think that would be something that would take up too much more code. From a programming perspective, it doesn't make much sense to me. Of course, hacking in general seems stupid to me, but that's beside the point.
Anyway, get protected, everyone! Update those antivirus programs, and run them immediately! Because if this hits you, it could do a lot of damage.