At the time of John Chapter 2, Yeshua had five Disciples following Him that attended the wedding in Cana where Yeshua turned the water into wine.  Through this event, we can see clearly how Yeshua taught in two ways.  He taught by what He said, and by what He did.  John writes that this first miracle manifested Yeshua’s glory and His Disciples believed on Him.    There were disciples following Yeshua and when they saw the miracle, they believed on Him.  Did they not believe on Him before?  The question is, if they did, why would the author or translator indicate to us that now, they believed on Him.  There are many places in the Bible where there are people who believed in Him, but didn't believe on Him.