"But you, brethren, are not in darkness, so that this Day should overtake you as a thief. You are all sons of light and sons of the day. We are not of the night nor of darkness. Therefore let us not sleep, as others do, but let us watch and be sober." 1 Thessalonians 5:4-6
While we do believe in a mid tribulation rapture, we are not saying we know the day or the hour. The Lord makes it very clear that no one but the Father knows that. While we do believe it is at or near the middle of the last 7 years of this age, the Lord says that He has to cut the time short for the elect's sake in Matthew 24:22 and who knows the amount of time that will be?