When was the beginning of Islam, and what is the time span between Prophet Muhammad and Jesus, peace be upon them both?

Islam began with the revelation descending upon the Prophet Muhammad, peace and blessings be upon him, in Mecca. This occurred on a Monday in the month of Ramadan, in his fortieth year, which was thirteen years before the Hijrah (the beginning of the Islamic calendar). This corresponds approximately to the year 608 or 609 CE. Salman al-Farsi mentioned that there were six hundred years between Muhammad and Jesus, peace be upon them both.