Combine the first 3 ingredients in a large bowl; cover date mixture, and let stand 24 hours.
Preheat oven to 325°.
Coat 2 (8 x 4-inch) loaf pans with cooking spray, and dust each pan with 2 teaspoons flour. Add the sugar, butter, vanilla, and egg to date mixture. Lightly spoon 2 1/4 cups flour into dry measuring cups, and level with a knife. Add flour and salt to date mixture, stirring just until blended. Divide the batter evenly between prepared pans.
Bake at 325° for 45 minutes or until a wooden pick inserted in center comes out clean. Cool the loaves 10 minutes in pans on a wire rack. Remove loaves from pans, and cool completely on wire rack.