According to this article there are three steps necessary to become one of Jehovah’s Witnesses. First is to learn what the Bible teaches by means of their free home Bible study program. Second is to put what they learn into practice.
Step 3: Get baptized. In the Bible, baptism is compared to a burial. (Compare Romans 6:2-4.) It serves as a symbol of dying to a past course of life and beginning a new one. Your baptism, then, is a public acknowledgment that you have completed the first two steps described by Jesus and are asking God for a clean conscience.—Hebrews 9:14; 1 Peter 3:21.
This question explains that before an unbaptized publisher is approved for baptism, they should attend congregation meetings and share in the work of spreading the message to other people and conducting home Bible studies with interested persons.
Previously, at the conclusion of the baptism talk, the speaker asked the baptism candidates to stand and answer the following two questions in a loud voice:
- Have you repented of your sins, dedicated yourself to Jehovah, and accepted his way of salvation through Jesus Christ?
- Do you understand that your baptism identifies you as one of Jehovah’s Witnesses in association with Jehovah’s organization?
Only after an associate has been baptized do they come under the authority of the Governing Body and the Elders and become recognized member of the organization.
During service years 1985, 1986, 1988 and 1990 over 155,000 Witnesses were disfellowshipped or "excluded" mainly for sexual immorality or gross misconduct. A Witness can only be disfellowshipped if they have been baptized.
https://wol.jw.org/en/wol/d/r1/lp-e/1986003#h=43
https://wol.jw.org/en/wol/d/r1/lp-e/1987683#h=16
https://wol.jw.org/en/wol/d/r1/lp-e/1989884#h=14
https://wol.jw.org/en/wol/d/r1/lp-e/1991843#h=36
The 2023 statistics show that 8.6 million people worldwide (annual average) have been recorded as associating with Jehovah's Witnesses based on the number who are actively engaged in proselytizing but that does not tell us how many are baptized members who are answerable to the organization.