Consider the way so promptly Simon, Andrew, James and John follow Jesus. Context will help up. John has just been arrested. John was very popular. John was winning converts. John was a believable. John was courageous in speaking openly about the need to repent. What impact did his arrest have on his followers? How many were scandalized by Herod's treatment of John. John's voice which had cried out was now silenced.
Enter Jesus, with exactly, literally, the same message as John. Those who had been well-prepared by John flocked immediately to Jesus, recognizing the same message which had already compelled them to change their lives.
Let's not detach the call of the first disciples from the John preaching the message of conversion. Jesus, by picking up where John left off, gave credibility to what John had begun and then fulfilled it beyond everyone's imaginings.
Conversion is key. God has a plan for us. Mercifully the precise details of the way his plan unfolds for each of us are hidden to us. Conversion, returns us and orients us properly toward God's destination for us. Let's respond promptly to that call having prepared by a constant turning away from sin.