PreScheds may be either Weekly or Monthly.  Weeklies trigger each Thursday or Friday.  Monthlies trigger on the first calendar day that you launch PestaRoo in a given month. So, even if the 1st and 2nd days of a month are holidays, when you come in to work on the 3rd, the Monthly PreScheds will then fire. In each case, PestaRoo goes through each PreSched and checks each one to see if its interval means it is ready to trigger.