On what Gregorian date was the revelation first descended? Thank you.

The revelation descended upon the Prophet, peace and blessings be upon him, on August 10, 610 CE, as authenticated by Al-Mubarakpuri in "The Sealed Nectar." It is important to pay attention to the Hijri calendar and the lunar months, due to Allah Almighty's saying: "Indeed, the number of months with Allah is twelve months in the Register of Allah from the day He created the heavens and the earth; of these, four are sacred. That is the the correct religion." And due to the Prophet's, peace and blessings be upon him, saying: "The year is twelve months, of which four are sacred: three consecutive ones: Dhul-Qa'dah, Dhul-Hijjah, and Muharram, and Rajab of Mudar which is between Jumada and Sha'ban." Al-Qurtubi and Al-Shawkani mentioned that this verse indicates that religious rulings are related to the Arabian lunar months, and not to the months of the non-Arabs, Romans, or Copts.