The elect will recognize the appearance of the antichrist, which is the start of the tribulation. We cannot put a date on the day of his appearance now - no man can. But, when the antichrist is here, only the elect will know "what time it is" as prophecy comes to pass. The rest of the world will believe him to be the messiah. They'll believe it to be the Second Advent.
Revelation 12
7 And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
8 And prevailed not; neither was their place found any more in heaven.
9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
This takes place at the sounding of the Sixth Trumpet, which marks the beginning of the tribulation that you are referring to. Therefore, we could not be in the middle of it now. It will not go unnoticed, as we are told...
Matthew 24:21
21 For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be.
Daniel 8:11 also documents Satan, the little horn, will take away the daily sacrifice. Satan is able to accomplish that as the world will stop taking Communion to Christ in remembrance of Him as they will believe Satan is Christ. We are told in Revelation 13:5 “there was given unto him a mouth speaking great things and blasphemies; and power was given unto him to continue forty and two months.“
Satan is allowed to continue 42 months. This reveals that Satan takes absolute control of the world at the midst of the week (one week of Daniel) as power is given to him. Make a note, 42 months is equal to 3.5 years, being half of the Tribulation. The entire Tribulation was originally seven years, but was shortened by Christ down to just a five month period (Matthew 24:22, Revelation 9:5).
On a side note - thank you for conversing this matter openly and fairly, something not shared by others here I've noticed.