*** w63 4/1 p. 200 Commemorating Christ’s Death ***
Particularly were those of this heavenly class called prior to 1931, during which time God held out only a heavenly hope to dedicating Christians. Those who have this hope should partake. But those whose hope is one of everlasting life in an earthly paradise, also promised in God’s Word, clearly should not partake; for they are not in the new covenant nor in the covenant for the Kingdom.
*** w61 3/15 p. 166 Should You Partake of the Lord’s Evening Meal? ***
Then, beginning in the 1870’s, God began to gather these together, and in 1919 began the fulfillment of Matthew 24:31, which says: "And he will send forth his angels with a great trumpet-sound and they will gather his chosen ones together from the four winds, from one extremity of the heavens to their other extremity." The facts show that at that time the call went out for more workers in God’s vineyard. This call continued until 1931, when, at the end of the "day’s" work in the vineyard, all the workers received their reward, the denarius, the name Jehovah’s witnesses.—Matt. 20:1-16.
*** w55 12/1 p. 709 Part 23—Expanding with a Trained Ministry ***
Next, over a period of 1900 years from Pentecost A.D. 33 to 1931, the "little flock" of 144,000 anointed ones were called out and unified in organized relationship to Jehovah as His witnesses. (Luke 12:32; John 17:21)