@Duran
These 5 trumpets are said to be blown and events associated with them end before the 3 1/2 years begin. (It is within the 6th trumpet that the 42 months are said to occur.)
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You've described the problem exactly.
The interesting question is when the event announced in trumpet 6 will begin: for Rev 11:2 uses futurum for "trampling" and that it will last 42 months. And in Rev. 11:3 it is written, again using futurum, that "a (suggestion) will be given" to the two witnesses to prophesy (again futurum) 1260 days. For completeness, I add that the second woe ends in Rev. 11:14, and only then, the 3rd woe occurs, at the sounding of the 7th and final trumpet (see also Paul).
In my opinion, the two witnesses begin preaching shortly after the 7th trumpet sounds, that is when the 1260 days begin to be counted. And parallel to this, according to Rev 12:6, the woman, after the birth of the boy/man (Michael), flees into the wilderness for 1260 days.
So I interpret this passage to mean that the heavenly battle (Rev 12:7) between Michael and the dragon, lasts for those 1260 days, the time when the two symbolic witnesses prophesy on earth. After Satan is cast down to earth (so he persecutes the woman again, and is given "time, times, and half a time." Although this roughly corresponds to the length of 42 months, it does not mean that "time" corresponds to "year"). Soon after, the reign of the Beast occurs, which according to Rev 13:5 is to last 42 months, and at that time, I believe, the "trampling" of the court/Jerusalem, the 42 months announced in the 6th trumpet, also occurs.
I've also read the explanation that John applied "days" to the people and "months" to the "beast" to somehow distinguish these time periods while connecting the two.
This is my take on the events surrounding the 7th trumpet and the 1260 days / 42 months issue. I do not convert time periods to "days to years" because there is no reason to.