The order: 7 Seals, 7 Trumpets, 7 Vials. How long do these last? 7 years? No, there is no 7 Yr Tribulation period anywhere in scripture; no pre-trib Rapture; no 70th Week of 7 Years for a New Israel Dispensation. That is all made up nonsense.
The first 4 Seals are the 4 Horsemen which bring on death and destruction on a worldwide scale; 5th Seal is the Altar of Martyrs beheaded for the witness of JESUS. 6th Seal is Heaven departing i.e. nobody from here on out will be able to accept JESUS as LORD and Savior. This likely because it coincides with the “Strong Delusion” and “Mark of the Beast”. 7th Seal is JESUS sealing the 12,000 from each tribe of Israel (no they are not Jehovah Witness).
7 Trumpets last 3 1/2 years guaranteed as described in 7 places 1260 Days, 3 1/2 years, Time, Times, Dividing of Time.
The 7th Trumpet is the day JESUS takes His Bride to Heaven. This is the mis-named Rapture described in 1 Thess 4:17 and 1 Cor 15:52.
Desolation results from the 2 Witnesses killed by Satan in Jerusalem; they rise first on the 7th Trumpet, followed by those living and those dead in Jesus. They are killed “Mid-week” 3 1/2 days before the 2nd Coming; we can see this in the time span of the 5th-6th Trumpet; the 5th Trumpet being 5 months (150 days) plus the 6th Trumpet 1 year, 1 month, 1 week, 1 day, 1 hour.
7 Vials of God’s Wrath is then poured out on the Desolate in one Day; the last day. JESUS returns to destroy everyone gathered and now dead (blood to the level of the horse bridles in Armageddon aka Valley of Slaughter) and everything man has built including the 3rd Temple of Antichrist.
The Millennium begins on this day and everyone in the Millennium will conduct a Hajj to Jerusalem on Feast of Tabernacles (Zech 14:19).
So the question is still how long does all this last? 2300 days; as told in Dan 8. Whether this has begun or not I don’t know.