How long mail takes is going to depend on many factors along the way. Many factors, indeed, though with regard to how long does priority mail take, the answer is, not long. In fact, the United States Postal Service says your package or envelope will arrive within two days.
Both the 2009 IRC and the DCA6-09 allow #2 southern pine 2x10s to span 13 feet 1 inch at 24 inches on-center at a design load of 50 psf. That means these joists can span the 12-foot depth of the deck, and the beam can be located at the perimeter. Nine joists will be needed for the 16-foot width.
A single 2x4x10' can be changed out for $7 when doing yourself, though figure at least $75 bare minimum to get a deck person out on premises (one with whom you are on good terms with, for about 1/2 day) and that may cover little more than several slats. Although in reality, others may want $125 for the same project.