It has been stated in traditions that whosoever recites this hadith for forty days in the morning, he/she will be one of the companions of Imam Zaman (a.s.) and …[1]. Conclusion: Dua Ahd needs to be read in the morning, and the best time to read it is after the
For further information, see:
Dua ahd and its recitation time.
Dua ahd.
[1] سَمِعْتُ سَیِّدَنَا الْإِمَامَ جَعْفَرَ بْنَ مُحَمَّدٍ الصَّادِقَ ع یَقُولُ مَنْ دَعَا إِلَى اللَّهِ أَرْبَعِینَ صَبَاحاً بِهَذَا الْعَهْدِ کَانَ مِنْ أَنْصَارِ قَائِمِنَا ع وَ إِنْ مَاتَ أَخْرَجَهُ اللَّهُ إِلَیْهِ مِنْ قَبْرِهِ وَ أَعْطَاهُ اللَّهُ بِکُلِّ کَلِمَةٍ أَلْفَ حَسَنَةٍ وَ مَحَا عَنْهُ أَلْفَ سَیِّئَةٍ وَ هُوَ هَذَا الْعَهْد
Bihar-ul-Anwar, v.83, pg. 284.