We already know this . Actually you can know with precision all the beginning of all the lunar months.
To calculate when a new lunar month begins we need to know two facts, the first is the exact time of the birth of the new moon, and the second fact is the exact time of the sunset of the same day. The new lunar month begins theoretically at the birth of the new moon, but begins practically at the first sunset to follow the birth of the new moon. God already gave us enough knowledge to calculate the beginning of the first day of Ramadan for the next hundreds of years. Sighting of the moon, to determine the new Islamic month, is an invention by the scholars that they took after the Jewish Rabbis who insist on sighting of the moon for their Jewish Lunar months. Sighting of the moon is not in the Qoran, but was a way of recognizing the beginning of the lunar month for those who lived in the desert and have no other means to recognize the beginning of the new month. God in the Qoran reminds us that the phases of the moon are only a tool to calculate the calendar and the time for pilgrimage (Hajj), see 2:189. God never said in the Qoran that sighting of the crescent moon is a requirement to determine the beginning of the new lunar month.
God is all Omniscient, Knower of everything, He knows that different generations will have different means of calculating the time of the birth of the new moon. Now, with all the knowledge we have, we cannot sit still knowing that the month has already started and wait for a scholar to go look for the crescent moon that may or may not be visible because of many factors, the most common of them is the weather condition.
For example this website gives you the times in America but you can convert for any country in the world.
the New Moon times at:
https://www.cnmoc.usff.navy.mil/usno/To convert the Universal time to your local time:
https://www.dxing.com/utcgmt.htmGOD bless.
Peace.
