The "two witnessing" role and the "third witnessing" role (by the 144,000 servants of The LORD) will be after the Rapture of the bride of Christ during The Great Tribulation period.
Ephesians 3:1~21 ‘“(God’s Marvelous Plan for the Gentiles) For this reason I, Paul, the prisoner of Christ Jesus for the sake of you Gentiles—Surely you have heard about the administration of God’s grace that was given to me for you, that is, the mystery made known to me by revelation, as I have already written briefly. In reading this, then, you will be able to understand my insight into the mystery of Christ, which was not made known to people in other generations as it has now been revealed by the Spirit to God’s holy apostles and prophets. This mystery is that through the gospel the Gentiles are heirs together with Israel, members together of one body, and sharers together in the promise in Christ Jesus. I became a servant of this gospel by the gift of God’s grace given me through the working of his power. Although I am less than the least of all the Lord’s people, this grace was given me: to preach to the Gentiles the boundless riches of Christ, and to make plain to everyone the administration of this mystery, which for ages past was kept hidden in God, who created all things. His intent was that now, through the church, the manifold wisdom of God should be made known to the rulers and authorities in the heavenly realms, according to his eternal purpose that he accomplished in Christ Jesus our Lord. In him and through faith in him we may approach God with freedom and confidence. I ask you, therefore, not to be discouraged because of my sufferings for you, which are your glory. For this reason I kneel before the Father, from whom every family in heaven and on earth derives its name. I pray that out of his glorious riches he may strengthen you with power through his Spirit in your inner being, so that Christ may dwell in your hearts through faith. And I pray that you, being rooted and established in love, may have power, together with all the Lord’s holy people, to grasp how wide and long and high and deep is the love of Christ, and to know this love that surpasses knowledge—that you may be filled to the measure of all the fullness of God. Now to him who is able to do immeasurably more than all we ask or imagine, according to his power that is at work within us, to him be glory in the church and in Christ Jesus throughout all generations, for ever and ever! Amen.”’
Revelation 14:1-5 “Then I looked, and there before me was the Lamb, standing on Mount Zion, and with him 144,000 who had his name and his Father’s name written on their foreheads.” And I heard a sound from heaven like the roar of rushing waters and like a loud peal of thunder. The sound I heard was like that of harpists playing their harps. And they sang a new song before the throne and before the four living creatures and the elders. No one could learn the song except the 144,000 who had been redeemed from the earth. These are those who did not defile themselves with women, for they remained virgins. They follow the Lamb wherever he goes. They were purchased from among mankind and offered as firstfruits to God and the Lamb. No lie was found in their mouths; they are blameless.”