Matthew 28:19-20
Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.

If there was only one Christian in the world in 2024, and that Christian were to pray and God to use him to win one other person to Him and allow him to disciple him for one year. There would be two Christians in the world in 2025. If these two Christians were to be used by God to disciple two additional Christians for one year, there would be four Christians in 2026. How long would it take to win the world to Christ if every person responded to God and was discipled one on one?

2024—1 Christian
2025—2
2026—4
2027—8
2028—16
2029—32
2030—64
2031—128
2032—256
2033—512
2034—1000 (rounded here)
2035—2000
2036—4000
2037—8000
2038—16,000
2039—32,000
2040—64,000
2041—128,000
2042—256,000
2043—500,000 (rounded here)
2044—1 million
2045—2 million
2046—4 million
2047—8 million
2048—16 million
2049—32 million
2050—64 million
2051—128 million
2052—256 million
2053—516 million
2054—1 billion (rounded here)
2055—2 billion
2056—4 billion
2057—8 billion

It would take 33 years. The first person would have discipled 33 people. The last 4 billion people all would have discipled one each.