Here, I wrote that the 12 year cycle is like a day. Therefore over 6000 years, we have 500 days.
This is all based on Tekufat Nissan, so let's start with the world being created on the 1st of Nissan, and count forward 500 days.
Obviously the Hebrew calendar has its variances, for simplicity sake I used Nissan 5768 to Adar 5769 for determining month lengths.
Day number 500 is the 29th of Av, my birthday.
The 29th of Av is brought down by Rashi as the end of the 2nd period of 40 days. On the 29th of Av, Moshe attained forgiveness for the Sin of the Golden Calf. However, it was only 40 days later that the 2nd Luchot were received, on the 10th of Tishrei, Yom Kippur.
At the end of 500 days is forgiveness, but only 40 days later takes us back to before the sin itself.