Prayer: Is It Permissible to Join at the End of the First Row Before Those Between You and the Imam?

Practical Laws of Islam as per the teachings of Imam Khamenei

Prayer: Is It Permissible to Join at the End of the First Row Before Those Between You and the Imam?

English:

Question #576:

Is it permissible for one who is joining at one of the ends of the first line to enter the congregational prayers prior to those between him and the imam?

Answer #576:

When the followers standing between that person and the Imam are completely ready to enter the prayer after the Imam has started his prayer and are about to say takbīr, that person is permitted to start his congregational prayer.

-Imam Khamenei, Practical Laws of Islam, Importance and Conditions of Prayer