Luke 3:23 And Jesus himself began to be about thirty years of age
, being (as was supposed) the son of Joseph, which was the son of Heli,
This parable would strongly indicate that Jesus ministry was at least 3 years:
Luke 13:6 He spake also this parable; A certain man had a fig tree planted in his vineyard; and he came and sought fruit thereon, and found none.
Luke 13:7 Then said he unto the dresser of his vineyard, Behold, these three years I come seeking fruit on this fig tree
, and find none: cut it down; why cumbereth it the ground?
Luke 13:8 And he answering said unto him, Lord, let it alone this year also, till I shall dig about it, and dung it
Luke 13:9 And if it bear fruit, well: and if not, then after that thou shalt cut it down.