3 Bible Verses about Calendars

Concerning that day or hour no one knows, neither the angels of the heavens, except my Father only.

And He responding said to them, It being evening, you say, It will be fair weather: because the sky is red: and in the morning, It will be stormy to-day: for the lowering sky is red: ye hypocrites, you know how to discern the face of the sky: but are you not able to discern the signs of the times? A wicked and adulterous generation seeks after a sign. And no sign shall be given it, except the sign of the prophet Jonah. And leaving them, He departed.

The birth of Jesus Christ was thus: His mother Mary, having been betrothed to Joseph, before they came together, was found having gestation from the Holy Ghost.