I just cannot bring myself to believe that the Church Age will be some random number of years, days, and hours that will run until some arbitrary number is reached. You have said that the Rapture will occur when the full number of Gentiles have been brought in, and you have backed that assumption with some convincing scriptural references. I am sure that you are correct, but only because God knows the future and knows what the exact count will be on the date He has chosen for the Rapture to occur. There is so much in the Bible that is date specific that I cannot help but think the Rapture will be also.
A good example would include how the second Temple was destroyed on the exact same day of the year as the first Temple. Another example would be how Jesus rode into Jerusalem precisely 173,880 days ( 483 years) after the decree of Artaxerxes Longimonus. The Church Age began when the Holy Spirit was given in 32 AD on the first Pentecost. Wouldn’t it be logical to assume that the Holy Spirit will be taken back to heaven in the Rapture on Pentecost as well?
I’ve often said that if the rapture is meant to occur on a Jewish feast date, then Pentecost would be the most obvious choice. The problem is, how can you have a secret event on a day when everyone is expecting it? Of course God knows the date upon which the full number of the church will be reached, but I don’t think anyone on Earth will be able to predict it in advance. And after the fact, we’ll understand that neither the number nor the date were random or arbitrary, but were precise and make perfect sense, just like the dates of the Temple destruction and the date of the Lord’s coming. By the way, the precision of these dates was also only realized after the fact.