Every year UPS forecasts its busiest shipping day of the year - the day on which it delivers the most packages. They also usually predict how many packages they'll deliver on that day, but this year they are not, citing the economic times.
This year, the busiest UPS day will be Thursday, December 18. What does that mean for online sellers? Well, most UPS packages are three days in transit in the US, so to be delivered on the 18th, most of them were shipped on Monday the 15th. That means they were probably ordered a day or two before that on the weekend of Dec. 13-14.
And where were they ordered? Why on the internets, of course! So wipe "Cyber Monday" out of your minds and be ready for the real holiday rush next weekend.
(I don't find a forecast from FedEx, but the USPS is forecasting Dec. 17 as their busiest day. Canada Post's busiest day was Dec. 17 last year, I don't think they've issued a forecast this year - labor problems have been causing some delays there)