I believe that a person who shows interest in getting baptized should be taught and baptized right away and not wait for the next scheduled baptismal class. I believe that the average person can get a basic understanding of the scriptures from a 30 minute "conversation" that will "qualify" him for baptism. We just need to ensure that:
1. The person believes and confesses that Jesus is Lord and Savior.
2. The person has repented of their sins and has made a decision to follow Christ.
3. The person understands the purpose of water baptism and the formula that we are using (to differentiate from other churches that use a different one). And maybe tie it with the concept of the Oneness of God.
Almost all (if not all) of actual baptisms that took place in the book of Acts were preceded by some type of teaching or preaching.
Following up on the new convert is a different conversation but we cannot overemphasize the importance of
teaching before AND after baptism.
Matthew 28:19-20
19 Go ye therefore, and
teach all nations,
baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:
20
Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen.