Get a good map book, and look up the streets for each package before you leave the bldg. Write down the grid coordinates for each package, on the box near the label for easy reference.
You can than organize the packages to their respective grid coordinates and pages in the map book.
For example, you may have a stop at 123 Main St with the grid coordinates located on PG 84, A4.
You may have anoother pkg for 1600 Pennsylvania Ave located on PG 85, C3.
Most of your stops will be near eachother, and depending on the map book in use, will all be within the same 4-5 pages in the map book. So even though you may not initially know where every stop is located, you can still organize your stops before you leaving the building, and have a general idea of which stops are close to each other. You may find that you have 4 stops on Page 83, 2 stops on Page 84, and 1 stop on Page 85, etc...
This will help you get a starting point and get a general idea of where all of your stops are located.