Following the instructions of our Mufti, our Muath-thin only recites the Iqaamah when the Imaam reaches his musalla.

Answer

Usually a time is fixed for the Muath-thin to step forward and recite the Iqaamah whether the Imaam has reached the musalla or not. What your Mufti has implemented is also correct. There is, however, no valid excuse for the lagging musallis. It is not permissible for them to lazily file into the sufoof (rows) as was the practice of the munaafiqeen. They must ensure that they are in the rows in time and that they all begin the Salaat with the Imaam's Takbeer. Those who are sitting at the back should move forward quickly the moment the Muath-thin steps forward or begins the Iqaamah. Many musallis have the evil attitude of sitting and waiting for the end of the Iqaamah or for the Salaat to begin. Only then do they get up like the munaafiqeen (hypocrites) used to practice. The Qur'aan Majeed severely rebukes them for such indolence.