The term rabbi in the time of Jesus did not necessarily refer to a specific office or occupation. That would be true only after the Temple in Jerusalem was destroyed (70 AD). Rather, it was a word meaning great one or my master which was applied to many kinds of people in everyday speech. It clearly was used as a term of respect for one's teacher as well even though the formal position of rabbi would come later. In one sense then, calling Jesus Rabbi? is an anachronism. In another sense the use of this term for him by the people his day is a measure of their great respect for him as a person and as a teacher and not just a reference to the activity of teaching he was engaged in.
Many people referred to Jesus as Rabbi. His disciples (Luke 7:40), lawyers (Matt. 22:35-36), ordinary people (Luke 12:13), the rich (Matt. 19:16), Pharisees (Luke 19:39), and Sadducees (Luke 20:27?28). Jesus fit the description of a first century rabbi especially one at the most advanced level?the one sought by talmidim.