Sorry for the typo.
Just to clarify, regarding the imminent return of the Lord, I'm referring to the Lord's appearing to gather the church and taking them back to the Father's house in accordance with John 14:1-3 and 1 Thess.4:16-17, which takes place before God's wrath and before those cosmic signs mentioned. By your mentioning of those cosmic disturbances in Joel, Isaiah and Matthew, you are referring to the event of when the Lord returns to the earth to end the age, which takes place after God's wrath.
To answer your question, the imminence of the Lord's return 'to gather the church' began after the Lord ascended into heaven. That the Lord told Peter that he would die in his old age, does not interfere with the Lord's imminent return. Peter and everyone else who died would simply be resurrected, while the living in Christ would be transformed and caught up. But I see what you are saying. I guess that you could say that because of what the Lord told Peter, that he would have to die of old age before the Lord could return. When Paul wrote to the Thessalonians regarding the resurrection and the living being transformed and caught up he said "After that, [we] who are alive and remain will be caught up together with them in the clouds to meet the Lord in the air. By saying "We" Paul was including himself in the group of those who would be alive and caught up, which would infer imminence. Most place this letter as being written at 51-52 AD. In any case, if you want a benchmark, you could say that the Lord's coming has been imminent anytime after the first century. However, we in the future know that the Lord's coming to gather us is close, because among other proofs such as Israel becoming a nation, the current state of the world and the fact that the mark of the beast technology is here, we can see that the gathering of the church is very close to taking place.