"As JESUS walked by the lake of Galilee, HE saw two brothers, Simon called Peter, and Andrew his brother, casting a net into the lake, for they were fishermen. HE said to them, 'Come, follow ME, and I will make you fish for people."
At once they left their nets and followed HIM.
HE went on from there and saw two other brothers, James, the son of Zebedee, and his brother John, in a boat with their father Zebedee, mending their nets. JESUS called them.
At once, they left the boat, and their father, and followed HIM." - Matthew 4:18-22
(At once, they abandoned their nets and followed HIM, which means leaving their family and work they began to live with HIM. Like the masters of religion in HIS time, like the rabbis, JESUS instructed HIS first disciples, teaching them what they were to pass on to others in the Church.
Simon, Andrew, James and John. JESUS already knew them: HE had met them where John the Baptist was preaching [John 1:35]. The first nucleus of disciples is this natural group of lake fishermen of which Peter seemed to be the leader. They were most probably young men, ready to make a commitment at a time and in a culture where people were freer than we are from the constraints of work.
They did not yet know what the Reign of GOD would mean but they trusted JESUS to guide them. This for them was the beginning of faith.)