Acts 2:39-42. Peter tells the gathered Jews on the first Pentecost that the promise of Jesus Christ is for all of them, and their children, and those who are far off, and everyone who God calls to Himself. He exhorts them to save themselves from "this crooked generation", and testifies to them in many other words. Those who received Peter's word that day and were baptized were about 3,000 "and they devoted themselves to the apostles' teaching and fellowship, to the breaking of bread and the prayers."

In one day of preaching, Peter inspired 3,000 people to be baptized! Not only baptized, but fully devoted to the teachings of the Church (which is what the apostles are at this point), and in complete fellowship with it. This is the Holy Spirit at work! It could not have happened until the Spirit had inspired both Peter and his listeners, and God knew when that time was just right.

Peter's success shows the value and necessity of waiting until God tells us to act. If Peter had preached earlier, he would not have been so successful, and may have even turned people off and hurt the cause. Peter stayed in touch with God and obeyed Jesus, and because of that he was filled with the Holy Spirit and was able to speak words that converted thousands in one day.