Answer: Peter and Andrew followed Jesus "at once." James and John followed Him "immediately," (verses 20 and 22).
MORE INFORMATION AND/OR OTHER SCRIPTURE REFERENCES:
Obedience to the Will of God and Christ is immediate, ever ready and constant:
Psalm 119:60: "I will hasten and not delay to obey Your commands."
Luke 12:35-40: [Jesus said,] "Be dressed ready for service and keep your lamps burning, like men waiting for their master to return from a wedding banquet, so that when he comes and knocks they can immediately open the door for him. It will be good for those servants whose master finds them watching when he comes. I tell you the Truth, he will dress himself to serve, will have them recline at the table and will come and wait on them. It will be good for those servants whose master finds them ready, even if he comes in the second or third watch of the night. But understand this: If the owner of the house had known at what hour the thief was coming, he would not have let his house be broken into. You also must be ready, because the Son of Man will come at an hour when you do not expect Him."
Acts 22:16: "And now what are you waiting for? Get up, be baptized and wash your sins away, calling on His Name."
