I've found that if I pick USPS, they always arrive a day or two after the estimated delivery date. UPS seems to arrive on the scheduled date.
For those that mentioned weather- I ordered my first manufactured sponsored item on the 1st (estimated delivery 2/3), and it still hasn't shipped. I can't really complain because hey, it's free, but it does mean that much longer till I can order an EF sponsored item! But yeah, I'm guessing that the snowstorms have caused a lot of delays lately.