When does the time for "Al-Bakūr," mentioned in the saying of the Messenger of Allah, peace and blessings be upon him, "O Allah, bless my nation in its early mornings (Bakūr)," begin and end?

The Hadith "O Allah, bless my nation in its early mornings" was narrated by Abu Dawud, Al-Tirmidhi, Ibn Majah, and Ahmad. The "early morning" (bukur) refers to the beginning of the day, starting from the spread of the true dawn's light and the performance of the Fajr prayer, and ending at sunrise when the sun has risen and the time for Duha (forenoon) prayer begins. The Prophet, peace and blessings be upon him, specifically singled out the early morning in his supplication because it is the time when activities commence and people are energetic. Ibn Uthaymeen mentioned that many people nowadays sleep during the early part of the day, thereby missing out on this blessed time.