"As Jesus was sitting on the Mount of Olives, the disciples came to him privately. Tell us, they said, when will this happen, and what will be the sign of thy coming?" (Matthew 24:3)
Jesus told them what to look for...
"Jesus answered: Watch out that no one deceives you. For many will come in my name claiming I am the Messiah, and will deceive many...and many false prophets will appear and deceive many people" (Matthew 24:4, 11)
The sign of His coming is an era when many call Jesus the Messiah (Christ), but are deceiving themselves and others with false teaching. The Apostle Paul also speaks of this era.
"This know also, that in the last days perilous times shall come. For men shall be lovers of their own selves, covetous, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy, without natural affection, truce breakers, false accusers, incontinent, fierce, despisers of those that are good, traitors, heady, high minded, lovers of pleasures more than lovers of God; having a form of godliness, but denying the power thereof: from such turn away." (2 Timothy 3:1-5)
In such an era it will be hard to distinguish those who call themselves Christians from everyone else, at least outside the church building. And it is in such an era that another sign will appear in heaven.
"Then will appear the sign of the Son of Man in heaven. And then all the peoples of the earth will mourn when they see the Son of Man coming on the clouds of heaven, with power and great glory" (Matthew 24:30)
This sign is the actual return of Jesus. But no one knows the "day or hour" when this sign will appear in heaven.
But about that day or hour no one knows, not even the angels in heaven, nor the Son, but only the Father." (Matthew 24:36)
You can know the "year" and other signs are by simply studying the bible. Few do. Keep watching for His return. The salvation He brings at His return is the "blessed hope" for humanity, and we should live our lives as if it may occur today.
"For the grace of God has appeared that brings salvation to all people. It teaches us to say 'No' to ungodliness and worldly passions, and to live self-controlled, upright and godly lives in this present age, while we wait for the blessed hope—the appearing of the glory of our great God and Savior, Jesus Christ, who gave Himself for us to redeem us from all wickedness and to purify for Himself a people that are His very own, eager to do what is good. These, then, are the things you should teach." (Titus 2:11-15)