What message do the two witnesses proclaim when they begin preaching?
When the two witnesses begin preaching, they proclaim godly things, specifically the King and the Kingdom. Their preaching immediately announces that the King and the Kingdom are coming, just as Jesus said. This message sparks a response from the 144,000 young Jewish men.
Les teaches that since these two witnesses are beginning to proclaim godly things, they will be proclaiming the King and the Kingdom is coming out of their preaching immediately, echoing what Jesus said. He suggests that right off the very first week or so, their prophesying or speaking will produce a response from the 144,000 young Jewish men of chapter 7. These servants, Les feels, have been listening to the two witnesses and are responding. The context then describes four angels holding the four winds, another angel with the seal of the living God, and the command not to hurt the earth, sea, or trees until God's servants are sealed in their foreheads.