11:3 I will give power to my two witnesses,
and they will prophesy one thousand two hundred sixty days, clothed in sackcloth."
 

11:4 These are the two olive trees and the two lampstands,
standing before the Lord of the earth. (Zec 4:11-13)
11:5 If anyone desires to harm them,
fire proceeds out of their mouth and devours their enemies.
If anyone desires to harm them, he must be killed in this way.
11:6 These have the power to shut up the sky,
that it may not rain during the days of their prophecy.
They have power over the waters, to turn them into blood,
and to strike the earth with every plague, as often as they desire.

11:7 When they have finished their testimony,
the beast that comes up out of the abyss will make war with them,
and overcome them, and kill them.
11:8 Their dead bodies will be in the street of the great city,
which spiritually is called Sodom and Egypt, where also their Lord was crucified.
11:9 From among the peoples, tribes, languages,
and nations people will look at their dead bodies for three and a half days,
and will not allow their dead bodies to be laid in a tomb.
11:10 Those who dwell on the earth rejoice over them, and they will be glad.
They will give gifts to one another, because these two prophets tormented those who dwell on the earth.

11:11 After the three and a half days, the breath of life from God entered into them,
and they stood on their feet. Great fear fell on those who saw them.
11:12 I heard a loud voice from heaven saying to them, "Come up here!"
They went up into heaven in the cloud, and their enemies saw them.
11:13 In that day there was a great earthquake, and a tenth of the city fell.
Seven thousand people were killed in the earthquake,
and the rest were terrified, and gave glory to the God of heaven.
 

11:14 The second woe is past. Behold, the third woe comes quickly.

11:15 The seventh angel sounded,
and great voices in heaven followed, saying, "The kingdom of the world has become the Kingdom of our Lord, and of his Christ. He will reign forever and ever!"

11:16 The twenty-four elders, who sit on their thrones before God's throne,
fell on their faces and worshiped God,
 

11:17 saying: "We give you thanks, Lord God,
the Almighty, the one who is and who was{TR adds "and who is coming"};
because you have taken your great power, and reigned.
11:18 The nations were angry, and your wrath came,
as did the time for the dead to be judged,
and to give your bondservants the prophets, their reward, as well as to the saints,
and those who fear your name, to the small and the great;
and to destroy those who destroy the earth."

11:19 God's temple that is in heaven was opened,
and the ark of the Lord's covenant was seen in his temple.
Lightnings, sounds, thunders, an earthquake, and great hail followed.

"When the priests enter therein, then shall they not go out of the holy place into the utter court, but there they shall lay their garments wherein they minister; for they are holy; and shall put on other garments, and shall approach to those things which are for the people."Eze 42:14

The 42 months = 1260 days (with 360 days/ year as according to ancient calendars), is the period mention a number of times in Daniel and Revelations (See Timing Chart) in which the believer will experience a great deal of persection from the world. The believers are view as priests according to Rev 1:6.

vs 3-4 It seems consistent that the 1260 days mentioned here to be the same as the 42 months of vs 2. It is unclear whether the two witness are individuals or once again symbolic of the whole church. vs 4 associates these two with the prophecy in Zechariah concerning the two olive trees:

"Then answered I, and said unto him, What are these two olive trees upon the right side of the candlestick and upon the left side thereof? And I answered again, and said unto him, What be these two olive branches which through the two golden pipes empty the golden oil out of themselves? And he answered me and said, Knowest thou not what these be? And I said, No, my lord. Then said he, These are the two anointed ones, that stand by the LORD of the whole earth." Zec 4:11-14

"The hands of Zerubbabel have laid the foundation of this house; his hands shall also finish it; and thou shalt know that the LORD of hosts hath sent me unto you." Zec 4:9

"And speak unto him, saying, Thus speaketh the LORD of hosts, saying, Behold the man whose name is The BRANCH; and he shall grow up out of his place, and he shall build the temple of the LORD: Even he shall build the temple of the LORD; and he shall bear the glory, and shall sit and rule upon his throne; and he shall be a priest upon his throne: and the counsel of peace shall be between them both." Zec 6:12,13

In Revelations these two may correspond to two other people.  Some say Enoch and Elijah - the two who hadn't experienced physical death, or perhaps Moses and Elijah representing the Law and the Prophets. If this is the case, one can imagine a good number of Jews becoming Christians - as Paul prophecied in Rom 11:25,26

In Zechariah 4:2,3, these two olive trees are feeding oil to seven lamps. This could mean that they will bring life to the churches, bringing the nominal Christians to Christ, and thus unifying the body of Christ.

vs 5-6 These miracles are quite similar to those produced by Elijah and Moses.

vs 7 The beast is the AntiChrist.

vs 8-10 In view of Christ's crucifixion, it's not hard to imagine this hatred of these two. It doesn't take much for a mob to have such hatred. I could imagine they would be reckoned as alien invaders or demons or the like.

vs 11-13 According to the timing, their resurrection could correspond to the resurrection of all believers - known as "But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection.". (Rev 20:5) Thus the earthquake could represent the graves opening.

vs 15-19 Thus the resurrection would occur right at the last trumpet in accordance with 1Cor 15:52.

When does Christ start reigning on the earth? Actually it's on the seventh trumpet. Although not officially a part of the time of the Millenial Kingdom in which Christ will have his presence on the earth with the saints to reign for 1000 years, there is about a three year period in which from the clouds, Christ and his saints will have essentially a reign of terror in which wrath will be poured out on the unbelievers and the beast.