Early Christian Writings, Early Church Fathers:
http://www.earlychristianwritings.com/churchfathers.html
15 Tishri 3757 - Sukkot / Birth of Yeshua
15 Nisan 3790 - (30 C.E.) Pesach / Crucifixion of Yeshua
Yeshua was 30 when His ministry started, it lasted three and a half years and was crucified on Pesach. Throw out the 33 years, back up 6 months on the Hebrew calendar and you fall into Sukkot. There's lots more...