Answered by Shaykh Faraz Rabbani
Can I simply respond to the adhan at once?
In the Name of Allah, Most Merciful and Compassionate
May Allah’s peace and blessings be upon His Messenger Muhammad, his folk, companions, and followers
Walaikum assalam wa rahmatullah,
The sunna is to give the response to the adhan as the muezzin says the adhan. When busy, it is permitted to give the reply all at once after the adhan is given, as long as there wasn’t an undue delay, as understood from the major texts of the Hanafi school. [Ibn Abidin, Radd al-Muhtar]
However, it is the sunna to respond to the adhan as it is given–this should be our practice in normal circumstances.
And Allah alone gives success.
Wassalam,
Faraz Rabbani