John and Doves,
What triggers the 7 years tribulation? Let me go deeper to what triggers the tribulation with Paul's teaching.
In 1 Thessalonians 5, Paul says the day of the Lord shall come as a thief in the night.
2 For yourselves know perfectly that the day of the Lord so cometh as a thief in the night.
No one knows when will the thief come during the night. Basically Paul teaches no one knows when will the day of the Lord begin. The day of the Lord shall come as a thief in the night. And since day of the Lord is a term for 7 years tribulation, we learn it from Zephaniah 2, the beginning of 7 years tribulation is unknown to anyone. If it is the confirmation of covenant which begins the tribulation, and since there is preparation to this ceremony, it can't be unknown to nations and people, including Israel.
The only event which is unknown to us and shall come as a thief in the night is RAPTURE. Paul teaches rapture triggers the day of the Lord. It shall come as a thief in the night, unknown to anyone, catching everyone surprise, and triggers the day of the Lord aka 7 years tribulation.