Christians have suffered tribulation since the time of the Apostles, Jews who were the first Christians.
Belittling the suffering of Christians throughout the ages by pinpointing it the present or to a particular situation involving this one nation, the U.S. is ignorant and disrespectful. Plus, futurist eschatology was invented by Jesuits to point away from the Papacy being the Man of Sin, as was being revealed by Christians who suffered GREAT TRIBULATION at the command of the Papacy. (Jesuits also invented preterism to claim NERO was the Man of Sin for the same reason.)
As to when Christ Jesus returns, everyone will know because when that happens every single one of Mankind will be standing in front of the Judgment Seat of God with Him sitting on it.