Actually, we can rule out that date. The Bible says that no man knows the day that he
will come, but it doesn't say we can't know when he
won't come.
And he spake to them a parable; Behold the fig tree, and all the trees; When they now shoot forth, ye see and know of your own selves that summer is now nigh at hand. So likewise ye, when ye see these things come to pass, know ye that the kingdom of God is nigh at hand. (Luke 21:29-31 KJV)
Our calendars may have a specific date marked but, just from looking at the weather and what's happening in the natural world, can we really tell the exact date summer begins? Is there a discernable change that tells us spring has ended and sumer is now here? But even though I can't tell you exactly when summer will begin, I can tell you when it won't begin. It won't begin in February. It's the same with Christ's coming and the end of this age. I can't tell you exactly the date he will return, but I can tell you it won't be in May.
But how do I know this? All the annual festivals that God gave us have some prophetic meaning. Passover pointed to Christ's crucifixion, for example. Jesus was crucified on the day of Passover. The Feast of First Fruits forshadowed his resurrection, and he rose from the grave on that day. Pentecost prophesied the outpouring of the Holy Spirit, and that event took place on that day. The events forshadowed by the feast always happen on the feast days. There are a few different interpretations, depending on whether people believe that there will be a separate rapture, or whether the rapture and Christ's second coming are the same event, but people agree that it's one of the fall feasts that represents the rapture / second coming. The fall feasts all occur in the seventh month of the biblical calendar, which puts all the fall feasts (and, therefore, all the possible dates) in September to October of our calendar.