he was given a mouth speaking great things and blasphemies
As we have seen throughout this book, the actions and duration of the agents of evil are subject to Gods sovereign permission (Rev. Rev. 13:7+, Rev. 13:14-15+ cf. Luke Luke 22:31). The great things which he speaks are the pompous words which Daniel saw the little horn speak (Dan. Dan. 7:8, Dan. 7:11, Dan. 7:20, Dan. 7:25). In his exaltation of himself, Daniel saw him speak blasphemies against the God of gods (Dan. Dan. 11:36). The great things and blasphemies likely speak of the same thing. The figure [of speech] is Hendiadys; for the great things are his blasphemies.1 See #25 - Little Horn.
This period is equivalent to the time and times and half a time, a three and one-half year period during which Daniel saw that the saints would be given into the hand of the little horn (Dan. Dan. 7:25). 3 See Prophetic Year.
This period begins at the midpoint of the week, when he violates his covenant with many in Israel (Dan. Dan. 9:27) and overcomes the two witnesses (Rev. Rev. 11:7+) who had prophesied for 1,260 days (the first half of The 70th Week of Daniel). See Events of the 70th Week of Daniel. This is the time of Jacobs trouble which shall be for a time, times, and half a time; and when the power of the holy people has been completely shattered, all these things shall be finished (Dan. Dan. 12:7). During this time, the holy city is being tread underfoot by the Gentiles (Rev. Rev. 11:2+) and the woman, the Jewish remnant at the time of the end, is hidden in her place (Rev. Rev. 12:6+, Rev. 12:14+). See commentary on Revelation 11:2 and Revelation 12:6.
But when this Antichrist shall have devastated all things in this world, he will reign for three years and six months, and sit in the temple at Jerusalem; and then the Lord will come from heaven in the clouds, in the glory of the Father, sending this man and those who follow him into the lake of fire; but bringing in for the righteous the times of the kingdom, that is, the rest, the hallowed seventh day; and restoring to Abraham the promised inheritance, in which kingdom the Lord declared, that many coming from the east and from the west should sit down with Abraham, Isaac, and Jacob.Irenaeus, Against Heresies, v.xxx [emphasis added]4
2 Frederick William Danker and Walter Bauer, A Greek-English Lexicon of the New Testament and Other Early Christian Literature (Chicago, IL: University of Chicago Press, 2000), 682.
3 Christs public ministry was limited to three years and a half; so also will the Antichrists final ministry be (Rev. Rev. 13:5+).Arthur Walkington Pink, The Antichrist (Oak Harbor, WA: Logos Research Systems, 1999, 1923), s.v. Comparisons between Christ and the Antichrist.