“Behold, I am coming quickly, and My reward is with Me, to render to every man according to what he has done. I am the Alpha and the Omega, the first and the last, the beginning and the end.The Spirit and the bride say, ‘Come.’ And let the one who hears say, ‘Come.’ And let the one who is thirsty come; let the one who wishes take the water of life without cost.”

The period of time from the burning Bush to Israel exodus

How long did it take from the time Moses had a revelation of God on Mt. Sinai for Israel to exit Egypt?

People have different views, and it remains uncertain the length of time from the revelation at Mt. Sinai to Israel leaving Egypt. There is some information I found in the Codex Judaica. It is the Chronological Index of Jewish History. 

According to the Codex Judaica, the burning bush experience of Moses/Moshe occurred on the 15th of Nisan, which straddles our March-April calendar, and in the following year Israel exited Egypt. The plagues were ushered in on the 1st of Av, about the time of our July-August months. It further states that each plague occurred the first of each consecutive month with the last plague on the eve of Nisan 15 in 2448. 

The sons or Bnei Yisrael were free from slave labor on the 1st of Tishrei, which was about six months before Nisan 15. In commemoration of their redemption. The month of Nisan would then be considered their beginning of months where before it was Tishrei that led their new year. 

Mid. Yal. Sh. 4. 176/Bachya Sh. 10.5

Tal. R.H. 11 b, Tos

Bible Sh. 12.2, Ramban