Baptism in modern Christian denominations is often something that's done as a scheduled event for large groups every so often. It's often an interesting ritual that we wait to see as some "yeah, you're a Christian, guess they did this, too" mark. Ask yourself this: why did early Christians not wait?

How quickly was the Philippian jailer baptized? "And he took them that very hour of the night and washed their wounds, and immediately he was baptized." (Acts 16:33)

Paul was asked by Ananias, "Now why do you delay? Get up and be baptized, and wash away your sins, calling on His name.’" (Acts 22:16)

The Ethiopian himself asked, "Look, water! What prevents me from being baptized?" (Acts 8:36)

God's messenger urged Paul to not delay, and to be immersed immediately, washing away his sins. Why do we do differently today?