I'm not 100% positive but I think would have been between 32 and 33 yrs. As far as his age, I don't personally think that is am important issue. Probably of more importance, was the fact that being baptised was part of God's will for him (as God's word states "This is my son in whom I am well pleased"
The fact that he was baptised, by John the Babtist, as were others of that time, was to set an example of a testimony to the world and an example for like minded repented Christians to follow. His baptism was not the beginning of the creation of the Christian faith, but yet an example for us to follow.
The beginning of the Christian Faith, as I believe it to be, begins with the acknowledgement that Jesus is the one and only begotten son of the one and only true and living God. That Jesus was born, lived on this earth to show us the face and heart of God (his father), was slain and died upon the cross for every humanbeing's sin (we all have sin) every sin that ever was and ever sin that ever would be for all and all time. Rose from the grave on the 3rd day as was pretold and now sits at the right hand of God, to interceed for you and I and all who will accept these truths and ask him to forgive them, ask him to come and be the savior of their lives and live within their heart. This is the Cristian Faith, the baptism is a physical testimonial to the world of this faith, and in it's self alone has no power to save, not without acceptance of Jesus, and repentance. Thank you for allowing me an opportunity to witness my faith.