Two main parts
Jesus' earthly ministry, which encompassed the last 3 1/2 years of his life, can be divided into two main parts. The first part lasts roughly six months from the fall of 26 A.D. (where this timeline begins) to the spring of 27. Events in this period of include his baptism performed by John the Baptist and forty days of temptation by Satan in the Judean wilderness.
This latter part of this six-month period, after Jesus' baptism, includes his initial contact with many of the men who would become his apostles. Jesus also performs his first Biblically recorded miracle at a Cana wedding celebration, travels to his new home in Capernaum, and then journeys to Jerusalem to keep the first Passover of his ministry.
The second part or phase of Jesus' ministry, which lasts for three years until his crucifixion, begins during the Passover season of 27 A.D. It is during this special Holy Day period that he makes his presence, for the first time, publically known at Jerusalem's temple. He does so by throwing out the many merchants and "money changers" at the temple who were carnally benefitting in a place dedicated to worshipping the true God (John 2:13 - 25).
Fall of 26 A.D.
On Monday, September 2 in 26 A.D., Jesus turned thirty years old. This was the most important birthday in his entire life, as thirty was the Biblical age that needed to be reached before a priest could begin to serve God (see Numbers 4:3, 23, 47).
Jesus, after turning this momentous age, travels from his boyhood home of Nazareth (Mark 1:9) to Bethabara (John 1:28) to be baptized. Bethabara is located southeast of the Sea of Galilee on the eastern side of the Jordan River. It is the place where John the Baptist, for the past six months, has been calling for people to repent of their sins and be baptized (John 1:19 - 27).
Interestingly, John does not know in advance who exactly is the Messiah (John 1:31, 33). God has told him, however, to look for a special sign denoting who is His only Son. This sign (likely only visible to John), which will occur after the baptism, will be the Holy Spirit descending out of heaven and remaining on the person (ultimately Jesus).
John witnesses the sign of the Messiah immediately after the baptism when Jesus comes up from the Jordan River (Matthew 3:16, Mark 1:10). He sees God's spirit, like a dove, descend and remain upon Christ (Matthew 3:16, Mark 1:10, Luke 3:21 - 22, John 1:32 - 34).
John then hears a voice from heaven which says, "This is My Son, the Beloved, in Whom I have great delight" (Matthew 3:17, HBFV, see also Mark 1:11, Luke 3:22). This marks the first time God the Father (likely through an angel, since no one has heard his actual voice at any time - see John 5:37), from heaven, audibly confirms Jesus is His Son and endorses His ministry.
God's spirit, after his baptism, leads Jesus to travel from Bethabara south, along the eastern side of the Jordan, all the way down to the Judean wilderness located on the western side of the Dead Sea.
Jesus is led to a desolate area so that, while he is fasting, he can experience unparalleled temptations at the hands of God's great adversary (Matthew 4:1 - 11, Mark 1:12 - 13, Luke 4:1 - 13). His experience and overcoming of evil will spiritually prepare the Lord to begin, in just a few months, the second phase of his ministry.
Jesus' fast, and the devil's forty-day long marathon to tempt him, likely begins on the Day of Atonement (Yom Kippur) that occurred on Wednesday, September 11.
September 11 is especially appropriate for the beginning of Jesus' awesome struggle as it was the start, in 26 A.D., of the 50th or Biblical Jubilee Year that was to be heralded on Atonement. The Jubilee year is a time when liberty from debt, servitude and loss was to be proclaimed throughout the land (see Leviticus 25 and 27).
Both Matthew and Luke each list three specific temptations, directed at our Savior, toward the end of his fast. Satan's last subtle lies were chosen to appeal to any human-based weaknesses and desires Jesus might choose to indulge.
The first of the devil's last three temptations centered around trying to get Jesus to prove he was God in the flesh by immediately alleviating his hunger through a miracle (Matthew 4:3 - 4, Luke 4:3 - 4). His next temptation was to challenge the Lord to prove his Father's love by jumping off a high location to see if he would be kept from injury (Matthew 4:5 - 7, Luke 4:9 - 12).
The last, and perhaps greatest, temptation that came to Christ was to forego the prophetic trials, pain and tortuous death that awaited him and instead immediately rule over mankind (Matthew 4:8 - 10, Luke 4:5 - 8). The "catch" was that he had to worship the devil as if he were god and serve him instead of his Father.
Temptation ends . . . for now
Satan's concentrated temptations finally ended on Sunday, October 20, exactly forty days after they began. The devil will, of course, soon continue where he left off and tempt the Lord throughout his ministry.
After overcoming the temptation of the adversary, the "god of this world" (John 12:31, 2Corinthians 4:4) Jesus, in a weakened physical state, is ministered to by angels (Matthew 4:11, Mark 1:13). After what was likely a few days of regaining his strength, he makes the journey back to Bethabara and arrives there near the end of October (John 1:28).