What does Acts 2:41 mean?
In the course of a couple of hours, the infant church of Jerusalem has grown from 120 (Acts 1:15) to three thousand. Jesus promised His followers they would receive the Holy Spirit and be His witnesses, starting in Jerusalem (Acts 1:8). Long before, Jesus had told His disciples that the world was hungry for Him, if only there were people willing to teach (Matthew 9:37–38). He also told them they would do greater works than He—not in power but in scope (John 14:12). This is not the last great influx of believers. After this event, God will add "to their number day by day those who [are] being saved" (Acts 2:47). When Peter and John heal a beggar, five thousand men, besides women, will have come to follow Jesus (Acts 4:4). Eventually, even many of the priests will believe (Acts 6:7).This verse brings up the question of when a new believer should be baptized. In the New Testament church, people are baptized immediately upon accepting Christ as their savior, in one special instance even before receiving the Holy Spirit (Acts 8:9–17). How much do new converts need to understand? While many of the Jews and people who lived around Judea know about Jesus and how He fulfilled Judaism, the Philippian jailer and his family don't, and Paul and Silas see to their baptism right away (Acts 16:30–33).
The early believers are baptized right upon their conversion, and then trained in the doctrines of the faith. Over the course of history, as more false teaching assaults the church, training has been shifted to before baptism. This is intended so people understand their faith before publicly committing to it. Once someone claims to be saved and has demonstrated they understand what salvation is and the purpose of baptism, there's no theological reason to wait. Baptism is not required for salvation. It should be performed as soon after conversion as reasonable. Bear in mind that a core group of 120 believers baptized three thousand converts. Neither the baptism nor the training needs to be a complex production.