Pretribulational John Walvoord writes:

John Calvin, the great reformer, likewise looked for the imminent return of Christ. In commenting on 1 John 2:18, Calvin writes, “But the Apostle not only fortifies the faithful, lest they should falter, but turns the whole to a contrary purpose; for he reminds them that the last time had already come, . . . In the same way it behoves us to comfort ourselves at this day, and to see by faith the near advent of Christ, . . . nothing more now remained but that Christ should appear for the redemption of the world.” Even though Calvin did not follow premillennial truth, he nevertheless did believe in the imminency of the Lord’s return” (“Christ’s Olivet Discourse on the Time of the End: How Near is the Lord’s Return?,” p. 81, Bibliotheca Sacra, January 1972, John F. Walvoord).

What Walvoord fails to tell the reader is that Calvin believed in the imminent return of Christ, not because he thought the Church was raptured before Antichrist, rather Calvin believed the Antichrist was the papacy—hence, the reason Calvin believed that Christ could come back at any moment.
Here is the context of what Calvin continued to say in his commentary of 1 John 2:18, which was left out by Walvoord:

As ye have heard that antichrist will come. He speaks as of a thing well known. We may hence conclude that the faithful had been taught and warned from the beginning respecting the future disorder of the Church, in order that they might, carefully keep themselves in the faith they professed, and also instruct posterity in the duty of watchfulness. For it was God’s will that his Church should be thus tried, lest any one knowingly and willingly should be deceived, and that there might be no excuse for ignorance. But we see that almost the whole world has been miserably deceived, as though not a word had been said about Antichrist.

Moreover, under the Papacy there is nothing more notorious and common than the future coming of Antichrist [i.e., they did not recognize that he was already present]; and yet they are so stupid, that they perceive not that his tyranny is exercised over them. Indeed, the same thing happens altogether to them as to the Jews; for though they hold the promises respecting the Messiah, they are yet further away from Christ than if they had never heard his name; for the imaginary Messiah, whom they have invented for themselves, turns them wholly aside from the Son of God; and were any one to shew Christ to them from the Law and the Prophets, he would only spend his labor in vain. The Popes have imagined an Antichrist, who for three years and a half is to harass the Church. All the marks by which the Spirit of God has pointed out Antichrist, clearly appear in the Pope; but the triennial Antichrist lays fast hold on the foolish Papists, so that seeing they do not see. Let us then remember, that Antichrist has not only been announced by the Spirit of God, but that also the marks by which he may be distinguished have been mentioned.

This is consistent with the Prewrath position. When Antichrist appears and persecutes the Church, then Christ’s Return will be imminent! (but prewrath does not believe the pope is the Antichrist).