As for the chronology of when these 144,000 Jewish evangelists emerge on the scene, I personally believe this event occurs in the early part of the tribulation period, sometime after the rapture. Some Bible expositors suggest that the 144,000 must engage in their work of evangelism early in the tribulation, for the believers who are martyred in the fifth seal judgment (Revelation 6:9-11) are among the fruit of their labors, and the seal judgments are definitely in the first half of the tribulation period.
