We have no way of knowing until he comes to power. He may not be born, he could be a toddler, or he could be a teenager. We just cannot know yet. He'll come to power after the Rapture. I plan on being taken with the Rapture. If you aren't taken, you're not a Christian.
Since Satan does not know the day or hour( remember, that Jesus said that no one knows the hour except God Himself!) Therefore Satan has to keep 'somebody' in the 'wings'( off stage) At all times. Perhaps if Christ had come back in the 30's-40's it might have been Stalin or Hitler. More recently , it might have been alahkomanie/ the Libian ,Kadaffie/ Sadam Husinne(sp)- bin-ladin! Perhaps in past history in could have been Nero! Scripture says that Christ will come back BEFORE the tribulation of 7 years. In the last half of that 7 yr time, the anti Christ will rise to power! So.... If you think you know WHO the antiChrist IS, perhaps you have been LEFT BEHIND (not been caught up in the rapture) NOW:speaking of the THREE antiChrist: look at it like this: Satan wants to be like God(so he wants 3 persons with him too!) he will have 1: the false prophets 2: the AntiChrist 3: Himself NOT 3 ANTICHRISTS! That (he thinks) will be 'his' Father, son and Holy spirit'! Ya see?