In Matthew 24:37, Jesus spoke about a future period of time that he called his “presence.” This "presence" was closely tied to the establishment of the Kingdom.
Jesus' disciples asked when his presence would come and when the conclusion of the system of things would be. (Matthew 24:3)
Jesus went on to describe to them "signs" that would take place that would mark his presence.
Among these signs, he said that "this good news of the kingdom will be preached in all the inhabited earth...and then the end will come." (Mt. 24:14) Jehovah's Witnesses are preaching about this kingdom all over the world right now.
More about the Kingdom:
God’s Kingdom - What Is It? When Will It Come?