[JimSEA]

Muhammad frequently retreated to Mount Hira, a place of privacy and contemplation near Mecca, to meditate and consider his spirituality. Islamic tradition relates that it was during one such trip, in 610, when he was 40 years old, that Muhammad first heard the voice of the angel Gabriel, who recited to him the word of God, today written down in the Muslim holy book, the Qur'an, meaning "recitation."

The above quote, taken from an Islamic web site, makes a strong case for 610 AD as the beginning point although others would argue for 570 AD when Muhammad was born. I am OK with either date :)

[hardworking]

others would argue for 570 AD when Muhammad was born. I am OK with either date

Personally I prefer to think that it began when God expelled Satan, since Mohammad is one and the same.