My main focus is on Jesus' description of the Day of the Lord coming “as a thief in the night” (Matt 24:42, Luke 12:40 – there is no reference in Mark or John; Jesus refers to it again in Rev 16:15).
The apostles continue using this phrase in 1 Thes 5:2, and 2 Pet 3:10. (2 Thes 2 also talks some about the Coming of our Lord.)
Matthew says "Watch therefore: for ye know not what hour your Lord doth come" (Luke is similar in content).
It might be argued from 1 Thes 5:4 that Christians can know the hour (that it is non-Christians who are taken by surprise), but verse 6 still calls for us to be watchful – there is no mention of any events for us to look for which would signal the Second Coming.
We see the opposite in 2 Thes 2. Apparently, some false teachers told the Thessalonians that the Day of the Lord was upon them (v2, they had been in effect “left behind”). Here Paul proves to them they are not in the last days, as there would be several very clear signs.
The other possible counterpoint is Rev 3:3 (letter to Sardis). Here the context is not the Day of the Lord; but related – judgment against a local church.
II) The Fullness of Wrath in Judgment
This is counterbalanced by the giving of several very specific time frames for events during the Great Tribulation, as God's wrath is poured out through many specific, supernatural signs.
Rev 9:5 - 5 months
Rev 11:3 - 1260 days
Rev 13:5 - 42 months
Additionally, there are the events of the 21 judgments which are played out sequentially. Many charts have been drawn up which detail much of this period, and which could be used to reliably determine the coming of Jesus.
So then, we have an apparent contradiction – Jesus comes as a thief in the night, totally unexpected. Yet, we have Jesus' coming preceded by very specific, well-timed events (of unmistakeably supernatural proportions).
How can we resolve this contradiction?
The Rapture comes as a thief in the night, where we are “gathered unto Him” for we are “not appointed unto wrath”, and at some point after, the well-timed events begin their march to the close of history. The wrath of God poured out unto judgment.