God has carved out a future chunk of history by ordaining a 7-year period commonly called the “70th Week of Daniel” (and misleadingly called “The Tribulation Period”). This 7-year period is divided in two halves of three and one half years each (1,260 days, or 42 months).
It is noteworthy that in Daniel and Revelation there is only one half of this 7-year period that is the focus of key events–the latter three and one half years. Further, both Jesus and Paul in their discourses on the end of the age use Daniel as a source of their exposition. And the astute student will observe that both Jesus and Paul focus on the events that will unfold during the second half with an emphasis on the midpoint event: the revelation of Antichrist and the genesis of his plan to persecute the Church.
In Revelation we are introduced to two individuals known as the “Two Witnesses” who will minister on behalf of God and whose ministry has a particular purpose. There are often two discussions about these witnesses: their identification, and the time frame they minister in.
It is not the purpose of this article to discuss the former, only the latter. We are told that their ministry will last three and one half years (Rev. 11:3). Though the book of Revelation gives us precise correspondence that their time frame of ministering will be in the latter half of the 70th week of Daniel, there are some, especially with pretribulational assumptions, that force them to minister in the first half of the 70th week of Daniel with no Biblical warrant.
Given the information of when they will die (Rev. 11:7-10), it is demonstrated that they minister during the second half. Consequently, they die and are resurrected after the sixth trumpet is blown (9:13; 11:7) and after the second woe (9:12), but before the seventh trumpet (11:11,14,15).
And since their days of ministering is 1,260, the day of their death signals that the 70th week of Daniel was completed the day before. Thereby, it necessarily follows that the seventh trumpet is blown after the completion of the 70th week, in which the bowls of God’s final wrath will unfold in rapid succession.
There are many who have assumed that the seventh trumpet and the bowls must occur within the 7-year period, but a natural reading does not allow for this; hence the reason why it is common to see forced readings of these events placed in the 70th week. However, numerous students of prophecy are not aware that Scripture teaches an extra 75-day time frame that follows the 7 years, which is made up of a 30-day period and a 45-day period (Daniel 12:11-12). Incidentally, Robert Van Kampen did an exceptionally good job in expounding on these extra 75 days in his book The Sign.
Giving all this as a preface to this subject, I will direct you to this article in which the author unpacks it further.