Early Davening

Question: I need to be at work early, requiring me to daven before the earliest time to put on Talit and Tefillin. Which is preferable – to put them on without a blessing and before Barechu move them and recite the blessing or put them on before Barechu?
Answer: Either way is acceptable. This exact question is discussed by Rav Ovadiah Yosef in Shut Yechaveh Da'at vol. 2 #8.