I have heard from other Christians that Jesus is coming between 2030 and 2033. In this time period the 2000 years after the resurrection, which took place between 30 and 33 AD, will be full. From the first sin of Adam to the resurrection of Jesus is 4000 years, and from the resurrection to 2030-2033 is 6000 years. And the eternal Sabbath will take place.
Is this theory Biblical?
No.
Given an historical Jesus, there's a fair argument that he was a follower of John the Baptist and like John was essentially a preacher of the end times, that is, the imminence of God's direct intervention on earth to establish a world theocracy headed by the 'Son of Man', which appears to refer to Jesus himself.
The central texts are ─
Mark 9:1 And he said to them, “Truly, I say to you, there are some standing here who will not taste death before they see that the kingdom of God has come with power.”
Mark 13:28 “From the fig tree learn its lesson: as soon as its branch becomes tender and puts forth its leaves, you know that summer is near. 29 So also, when you see these things taking place, you know that he is near, at the very gates. 30 Truly, I say to you, this generation will not pass away before all these things take place.
Matthew 10:23 When you are persecuted in one place, flee to another. Truly I tell you, you will not finish going through the towns of Israel before the Son of Man comes.
Matthew 16:28 Truly, I say to you, there are some standing here who will not taste death before they see the Son of man coming in his kingdom.”
Matthew 24:32 “From the fig tree learn its lesson: as soon as its branch becomes tender and puts forth its leaves, you know that summer is near. 33 So also, when you see all these things, you know that he is near, at the very gates. 34 Truly, I say to you, this generation will not pass away till all these things take place.
Luke 9:27 But I tell you truly, there are some standing here who will not taste death before they see the kingdom of God.”
That is, when the author of Mark included these ideas in his gospel around 75 CE, they were copied by the authors of Matthew and of Luke synoptically in the mid-80s CE.
Informatively, they don't appear in John (mid-90s CE). The inference is that the claims were no longer tenable so the Second Coming would have to be redescribed to fit the obvious fact that virtually no one who could have been in Jesus' audience was still alive.
And with the ordinary pragmatism of politics, no alternative date was specified.
So as it was in the beginning, it is now and ever shall be, the Second Coming is the day after mañana.
If this is true, then the beast which is the revived kingdom should appear any moment.
They've been saying it in every age for two thousand years, so I suggest you don't hold your breath.