The time for the pre-dawn meal is between the middle of the night and dawn. It is considered best to delay it (that is, as close to dawn a possible). Zaid ibn Thabit reported: “We ate the pre-dawn meal with the Messenger of Allah and then we got up for the prayer. He was asked: ‘What was the amount of time between the two?’ He responded: ‘[The time it would take to recite] fifty verses.'” This is recounted by al-Bukhari and Muslim.
‘Amr ibn Maimun adds: “The companions of Muhammad, upon whom be peace, would be the first to break the fast and the last to eat their pre-dawn meals.” This is recorded by al-Baihaqi with a sahih chain.
Abu Zharr al-Ghafari related that the Prophet said: “My nation will always retain some goodness as long as they hasten breaking the fast and delay eating the pre-dawn meal.” This hadith has in its chain one Sulaim ibn Abu Uthman who is unknown.