39 But further, as to John's statement, that “after this He went down to Capharnaum, He and His mother, and His brethren and His disciples; and they continued there not many days;” it is uncertain whether by this period these men had already attached themselves to Him, in particular Peter and Andrew, and the sons of Zebedee. For Matthew first of all tells us that He came and dwelt in Capharnaum, and then that He called them from their boats as they were engaged in fishing.
On the other hand, John says that His disciples came with Him to Capharnaum. Now it may be the case that Matthew has but gone over here something he had omitted in its proper order. For he does not say, “After this, walking by the sea of Galilee, He saw two brethren,” but, without any indication of the strict consecution of time, simply, “And walking by the sea of Galilee, He saw two brethren,” and so forth: consequently it is quite possible that he has recorded at this later period not something which took place actually at that later time, but only something which he had omitted to introduce before; so that the men may be understood in this way to have come along with Him to Capharnaum, to which place John states that He did come, He and His mother and His disciples: or should we rather suppose that these were a different body of disciples, as He [may already have] had a follower in Philip, whom He called in this particular manner, by saying to him, “Follow me”?
For in what order all the twelve apostles were called is not apparent from the narratives of the evangelists. Indeed, not only is the succession of the various callings left unrecorded; but even the fact of the calling is not mentioned in the case of all of them, the only vocations specified being those of Philip, and Peter and Andrew, and the sons of Zebedee, and Matthew the publican, who was also called Levi. The first and only person, however, who received a separate name from Him was Peter. For He did not give the sons of Zebedee their names individually, but He called them both together the sons of thunder.
Source: The Harmony of the Gospels (New Advent)