What has the Church been doing for the last 1900 plus years?
According to the context, for the last 1900 plus years the Church has been accumulating, as people are brought into the body of Christ. This process will continue until the body is filled, and then Christ will take it out at the Rapture.
Les explains that the Church Age began sometime between 30 and 40 A.D., when the body of Christ had its beginning. For the last 1900 plus years, the Church has been accumulating, and believers have been brought into the body. It will be filled, and Christ will take it out at what is called the Rapture.