In 457 BC Artaxerxes issued a decree to allow the Jews to establish worship and Jewish law in Judah. 69 weeks is 483 days…(69 weeks X 7 days in a week). If you consider a "prophetic day for a year" principle, you would add 483 years from the date of the decree in 457 BC. You arrive at 26AD, but you must add 1 year for the crossover year between BC and AD. You will then come to 27 AD. This is the year Christ started His ministry. Luke 3:23 states he was about 30 years old when He began to preach. This would place His birth at 4 BC.