Is an EU constitution a sign of the Antichrist coming to power?
The EU coming into constitutional government does NOT mean it is the Antichrist’s power base. The EU, however, could be, I'm convinced, the matrix or nucleus out of which that power bloc of Revelation 17: 12-13 will evolve. Even this is open to many questions.
Don't look for any time --either day, hour, week, month, or year--upon which to pin Christ's rapture of the Church. Just be ready at all times to meet Him face to face. Matthew 24: 44 is a good Scripture to look to. See also Luke 21:28.
Jesus’ coming to call His Church is imminent --that is, it can literally happen at any moment.
The signing of the covenant between the "prince that shall come” and Israel and its enemies, guaranteeing peace and safety, is the event that sets in motion the tribulation (Dan. 9:26-27). Christians will definitely be in Heaven before that takes place, because God's wrath will then begin falling, and Christians, according to Paul the apostle, are not appointed to God's wrath (read 1 Thess. 5:10-11).