Paul's evangelistic efforts were able to reach everyone in Asia by the time Acts 19:10 was written. This in spite of having no internet.
Also, don't forget, there was an indestructible force of 144,000 resurrected First-fruits saints (raised from Jewish graves around Jerusalem in Matthew 27:52-53) who were not bound with the normal limitations of ordinary men. Just how much evangelistic ground do you imagine just one resurrected saint could have covered in those days between AD 59/60 when Revelation was written until AD 66 when the Great Tribulation cranked up? Billy Graham's evangelistic efforts would have paled in comparison. And there were 144,000 of these indestructible, immortal individuals who would never get sick or die again, get tired, succumb to temptation, or have family obligations such as children or a wife to attend to. Conceivably, everyone in the entire world could have heard a gospel presentation from one of these 144,000 First-fruits resurrected individuals by the time AD 70 rolled around.