There is no set time for the iqaamah, but attention should be paid to the following:
If a person is praying alone, or a woman is praying in her house, then it is better to do the prayer at the beginning of its time, apart from ‘Isha’ and Zuhr in the event of intense heat. So you should pray the Sunnah prayer that precedes the obligatory prayer, then pray the obligatory (fard) prayer. That is because of the report narrated by al-Bukhaari (527) and Muslim (85) from ‘Abd-Allaah ibn Mas’ood (may Allaah be pleased with him), who said: I asked the Prophet (peace and blessings of Allaah be upon him), Which deed is best? He said: “Prayer offered on time.” I said: Then what? He said: “Honouring one’s parents.” I said: Then what? He said: “Jihad for the sake of Allaah.”
And the Prophet (peace and blessings of Allaah be upon him) said: “When it is very hot, wait until it cools down somewhat before praying, for intense heat is an exhalation from Hell.” Narrated by al-Bukhaari (537) and Muslim (615).
And Abu Hurayrah (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Were it not that it would be too difficult for my ummah, I would have commanded them to delay ‘Isha’ until the last third of the night, or halfway through it.” Narrated by al-Tirmidhi (167) and classed as saheeh by al-Albaani in Saheeh al-Tirmidhi.
With regard to praying in congregation in the mosque, there should be enough time between the adhaan and iqaamah for people to purify themselves, come to the mosque and offer the regular Sunnah prayers.
Shaykh Sayyid al-Saabiq (may Allaah have mercy on him) said in Fiqh al-Sunnah (1/100): There should be enough time between the adhaan and iqaamah for people to prepare for the prayer and come to the mosque, because the adhaan was prescribed for that purpose. Otherwise its benefit is lost. And the ahaadeeth that were narrated concerning that are all weak. Al-Bukhaari said: Chapter: How long should there be between the adhaan and iqaamah, but no (specific) amount of time was proven. Ibn Battaal said: There is no limit for that except enough to allow the time for it to begin and the worshippers to gather. End quote.
Al-Haafiz Ibn Hajar (may Allaah have mercy on him) said in Fath al-Baari (2/126), commenting on the words of Imam al-Bukhaari, “How long should there be between the adhaan and iqaamah”:
Perhaps he was referring thereby to the report narrated from Jaabir, that the Prophet (peace and blessings of Allaah be upon him) said to Bilaal: “Allow between your adhaan and iqaamah enough time for the eater to finish his food and the drinker to finish his drink, and for the one who has gone to the toilet to finish relieving himself.” This was narrated by al-Tirmidhi and al-Haakim, but its isnaad is weak, although it has corroborating evidence in the hadeeth of Abu Hurayrah and the hadeeth of Salmaan, both of which were narrated by Abu Shaykh, and in the hadeeth of Ubayy ibn Ka’b, which was narrated by ‘Abd-Allaah ibn Ahmad in Ziyaadaat al-Musnad. But all of them are weak, and it is as if he was indicating that there is no proof of a set amount of time for that. End quote.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked: Did the Messenger (peace and blessings of Allaah be upon him) define a set time between the adhaan and iqaamah?
The Prophet (peace and blessings of Allaah be upon him) used to offer the prayer at the beginning of its time, except for ‘Isha’. He would look at how the people gathered; if he saw they had already gathered, he would pray it earlier, and if he saw that they were slow, he would delay it, and he would stay in his house until the muezzin came and told him that the time for prayer had come, or sometimes he would go out to pray without being told.
So the Sunnah is to hasten to offer all the prayers except ‘Isha’, and Zuhr when there is intense heat. But with regard to the prayers which have regular Sunnah prayers that are offered beforehand, such as Fajr and Zuhr, one should pay attention to the people’s situation so that they can do wudoo’ after the adhaan and offer these regular Sunnah prayers. End quote.
Majmoo’ Fataawa al-Shaykh Muhammad Saalih al-‘Uthaymeen (12/190).
If the congregation of the mosque agrees that the iqaamah for prayer should be given at a certain time, or that is done at the direction of the awqaaf authorities, so as to avoid disputes, there is nothing wrong with that and it should be followed.
And Allaah knows best.