Acts 20:1-6
And after the uproar was ceased, Paul called unto him the disciples, and embraced them, and departed for to go into Macedonia.And when he had gone over those parts, and had given them much exhortation, he came into Greece, And there abode three months. And when the Jews laid wait for him, as he was about to sail into Syria, he purposed to return through Macedonia. And there accompanied him into Asia Sopater of Berea; and of the Thessalonians, Aristarchus and Secundus; and Gaius of Derbe, and Timotheus; and of Asia, Tychicus and Trophimus. These going before tarried for us at Troas. And we sailed away from Philippi after the days of unleavened bread, and came unto them to Troas in five days; where we abode seven days.
In Acts 20:1 Paul leaves Ephesus, from whence he had tearfully written the reproachful epistle "1 Corinthians", for Macedonia. He had sent Titus to Corinth ahead of his own arrival to discern the Corinthians' response to it. Paul expected Titus to subsequently travel by land through Macedonia to meet and report to him. After meeting Titus in Macedonia, Paul then and from there writes the epistle preserved as “2 Corinthians”.
I. Paul departs necessarily North by land from Ephesus to Macedonia. Consequently, he reaches Troas 2 Corinthians 2:12-13.
Furthermore, when I came to Troas to preach Christ's gospel, and a door was opened unto me of the Lord, I had no rest in my spirit, because I found not Titus my brother: but taking my leave of them, I went from thence into Macedonia.
II. Turning West into and through Macedonia, he necessarily passed Philippi. He then needs travel South to reach Achaia, here called Greece , which includes Corinth and Athens. He spends three months in Greece/Achaia during the Winter . He then returns back through Macedonia reaching Philippi. He sails from there after the days of unleavened bread , in Early Spring, to Troas , apparently having arrived in Philippi either during or immediately preceding the festival Acts 20:6.
This fulfills his stated itinerary in 1 Corinthians 16:5-8
Now I will come unto you, when I shall pass through Macedonia: for I do pass through Macedonia. And it may be that I will abide, yea, and winter with you, that ye may bring me on my journey whithersoever I go. For I will not see you now by the way; but I trust to tarry a while with you, if the Lord permit. But I will tarry at Ephesus until Pentecost.
So to summarize:
1) Paul first visits Corinth 1 Corinthians 18:1.
2) After a year and a half cf.Acts 18:11 he departs for Syria v.18, eventually settling in Ephesus Acts 19:1. At some point after leaving Corinth he sends his "initial" not preserved epistle mentioned in ! Corinthians 5:9. In this epistle he apparently expressed his desire to revisit Corinth a second time to provide a "second charisma". He claimed he would reach Corinth directly upon leaving Ephesus (so by necessary implication sailing straight across the Aegean) and only subsequently would travel {north} to Macedonia (then back to Corinth and then (by sea) to Syria or directly down to Judea) 2 Corinthians 1:15-16.
And in this confidence I was minded to come unto you before, that ye might have a second benefit; And to pass by you into Macedonia, and to come again out of Macedonia unto you, and of you to be brought on my way toward Judaea.
3) While in Ephesus , Paul changes his plan after he hears from the house of Chloe 1 Corinthians 1:11 of all the dissensions etc in Corinth and so sends his letter "with many tears" cf.2 Corinthians 2:4 now preserved as "1 Corinthians".
4) He subsequently sends Titus to perceive their response to the brusquely critical epistle's condemnations and exhortations. 2 Corinthians 12:18 I desired Titus, and with [him] I sent a brother. Did Titus make a gain of you? walked we not in the same spirit? [walked we] not in the same steps?
5) When he receives from Titus the account of their zealous repentance, as Titus and Paul meet in Macedonia cf. Acts 20:2 , he writes "2 Corinthians".
2 Co 7:6 Nevertheless God, that comforteth those that are cast down, comforted us by the coming of Titus.
Paul considers this latter epistle to substantiate the second visit to Corinth 2 Corinthians 13:2
"προείρηκα καὶ προλέγω ὡς παρὼν τὸ δεύτερον..." "I had told you before hand , and am foretelling you, as if present the second time...".
6) When he subsequently spends three months in Greece Acts 20:3 he apparently stays in Corinth so constituting the predicted third visit cf.2 Corinthians 13:1.
A.In Paul's initial second visit itinerary (reiterated in 2 Corinthians 1:15-16) he would come to Corinth before visiting Macedonia.
B.In the subsequent second visit itinerary in 1 Corinthians 16:5 he insists that he will [instead] go through Macedonia before visiting Corinth.
C. But in 2 Corinthians he defends this change of his second visit plans and speaks of meeting Titus in Macedonia en route to Corinth.
D. Ergo, the logic of his defense in 2 Corinthians 1:15-16 of passing through Macedonia to reach Corinth to fulfill his second visit's 1 Corinthians 16:5-6 changed from the initial "second charisma" planned itinerary rests on his not having as yet passed through Macedonia to reach Corinth for a second visit.
If he had already visited Corinth between 1 and 2 Corinthians whether through Macedonia or nay his arrival would have given literal conclusion to the entire controversy of his planned itinerary for a second visit.
He has not imparted a second benefit and his stated means for which (a visit) necessarily implies it requires his physical presence i.e. he has not made a second visit. He has not by the time of 2 Corinthians 1:15-17 visited them by (sic) by passing Macedonia for he defends in those verses his purposing the opposite (to come to them through Macedonia) and he writes while in the midst of passing through Macedonia , thus fulfilling his itinerary as stated in 1 Corinthians 16:5.
Conclusion:
A trip, either a brief or a substantial stay, by Paul whether or not through or by passing Macedonia to Corinth between 1 and 2 Corinthians would render the 1 Corinthians 16:5-6 itinerary defense in 2 Corinthians 1:15-17 anachronistic and superfluous. 2 Corinthians 13:2 Greek unambiguously in context states that the epistle of "2 Corinthians" itself constitutes the second visit.