"After these things came Jesus and his disciples into the land of Judaea; and there he tarried with them, and baptized." - John 3:22 KJV

"And they [John’s disciples] came unto John, and said unto him, Rabbi, he that was with thee beyond Jordan, to whom thou barest witness, behold, the same baptizeth, and all men come to him." - John 3:26 KJV

On the Day of Pentecost, Peter preached baptism.

"Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost." - Acts 2:38 KJV

On that day, 3000 more were added to the church, when they too were filled with the Holy Ghost and  baptized in Jesus name.

"Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls." - Acts 2:41 KJV