The Rapture will occur at Christ Second Coming when His angels will gather His elect to meet Him in the clouds.
“The Coming of the Son of Man. “Immediately after the tribulation of those days,
the sun will be darkened,
and the moon will not give its light,
and the stars will fall from the sky,
and the powers of the heavens will be shaken.
And then the sign of the Son of Man will appear in heaven, and all the tribes of the earth will mourn, and they will see the Son of Man coming upon the clouds of heaven with power and great glory. And he will send out his angels with a trumpet blast, and they will gather his elect from the four winds, from one end of the heavens to the other.” (Matthew 24:29-31)
The Tribulation comprises the hardships that Christ’s disciples will endure until the Rapture.
“For those times will have tribulation such as has not been since the beginning of God’s creation until now, nor ever will be. If the Lord had not shortened those days, no one would be saved; but for the sake of the elect whom he chose, he did shorten the days.” (Mark 13:19-20)
Click the following link to retrieve (Mark 13).
“Prepare for Tribulation,” physically and spiritually. Central to the spiritual preparation is ― The Warning and the Illumination of Conscience ― an outpouring of God’s infinite Mercy and Grace for Humanity. The sacrament of Penance is a preparatory step, and the Warning Package covers the event in detail.
Click the following links to retrieve a concise coverage of the Warning and the Illumination of Conscience.