At the time of sehri, he would recite between a half to a third of the Qur’aan Majeed in Tahajjud Salaah. In this manner, he would complete one khatam in Tahajjud Salaah every three days.

Over and above this, Imaam Bukhaari (rahimahullah) would make one khatam daily, during the day, and would complete it at the time of iftaar. On completing the khatam, he would engage in du‘aa and say, “At the time when a khatam is completed, du‘aas are accepted.”

(Tahzeeb-ul-Kamaal 24/446)