Matthew, Mark and Luke did agree that Simon (named Peter by Jesus) was the senior disciple. St. Luke gave a dramatic account of the calling of Simon to the discipleship:

2 And saw two ships standing by the lake: but the fishermen were gone out of them, and were washing their nets.

3 And he entered into one of the ships, which was Simon's, and prayed him that he would thrust out a little from the land. And he sat down, and taught the people out of the ship.

4 Now when he had left speaking, he said unto Simon, Launch out into the deep, and let down your nets for a draught.

5 And Simon answering said unto him, Master, we have toiled all the night, and have taken nothing: nevertheless at thy word I will let down the net.

6 And when they had this done, they inclosed a great multitude of fishes: and their net brake.

7 And they beckoned unto their partners, which were in the other ship, that they should come and help them. And they came, and filled both the ships, so that they began to sink.

8 When Simon Peter saw it, he fell down at Jesus' knees, saying, Depart from me; for I am a sinful man, O Lord.

9 For he was astonished, and all that were with him, at the draught of the fishes which they had taken:

10 And so was also James, and John, the sons of Zebedee, which were partners with Simon. And Jesus said unto Simon, Fear not; from henceforth thou shalt catch men.

11 And when they had brought their ships to land, they forsook all, and followed him. (Luke 5:2-11)

There were two kinds of disciples. It is unfortunate that the word "disciple" is used for both of these phenomena, considering the different meaning that they have. And because of this the entire Christian world has been in total confusion about the two meanings of "disciple".

The most common kind of disciple, was the disciple that heard, believed, and followed the teachings of the master who was teaching. Such a disciple could be almost absolutely anonymous for a while, even until the time when the rabbi asks of his disciples to come forth and receive baptism for the remission of sins. From then on discipleship could not be executed solely from ones own closet. All disciples but twelve belonged to this group of followers.

The other kind of disciple did not choose their master, but they were chosen by him!

16 Ye have not chosen me, but I have chosen you, and ordained you, that ye should go and bring forth fruit, and that your fruit should remain: that whatsoever ye shall ask of the Father in my name, he may give it you. (John 15:16)

At the time of Jesus there were twelve disciples like this. But this kind of discipleship was only a temporary calling, and it was to be replaced by another calling in the future. That other calling was the calling to the Apostleship.

Why didn't Jesus call them to be Apostles at once? Why did he choose to extend the temporary callings of disciples first? According to the Greek dictionary the word Apostle is derived from the Greek Apostolos, from Apostellein, meaning: to send away. And in the Christian Church this sending away was to preach, to lead, to heal the sick, to raise the dead, to cast out unclean spirits, to give the Holy Ghost, etc. At the time when they became called disciples they were in no way ready for any of the tasks of the apostleship. But Jesus knew that these were the men that God wanted him to call. So he called them to the preparatory apostleship, the called discipleship.