What is the most accurate calculation of Jesus' birth date?

I am trying to develop an accurate historical timeline (expressed on the Gregorian calendar) that includes the events surrounding the annunciation, birth, life, ministry, death, and resurrection of Jesus. I have come across a number of speculations in the 4-6 BC range for his birth, in the 25-30 AD range for the onset of his ministry, and in the 29-33 AD range for his crucifixion. I believe a persistent error in our Western tradition of designating Good Friday as the day of his crucifixion and Easter Sunday as the day he rose from the grave has developed as the result of a misunderstanding about when during the week the special Passover Sabbath occurred that year. Friday evening to Sunday morning does not reconcile with what Jesus said about being in the earth for 3 nights and 3 days before rising again (**see proposed alternate scenario here** ). This error could contribute to a number of other miscalculations about the dates I am looking for. Can any of you help me clarify the date problem and narrow this down further? Thanks!