Prayer: The Time for Adhan and Iqamah
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 921
Adhan and iqamah must be said after the time for prayer has set in. If a person says them before that time – whether intentionally or forgetfully – they are invalid, except in the case when the time of prayer sets in during a prayer and the prayer is ruled to be valid, as explained in Ruling 731.