May one going on an early morning journey put on tefillin before the halachic morning time?

Synopsis

One who must depart before dawn may put on tefillin early (even before dawn) because there is no concern of sleeping in them; however the blessing is recited only when the proper time arrives.

Rishonim
Early Acharonim
Late Acharonim
Lenient
Strict
Lesser cited
Major authority

Discussion

Discussion coming soon.

The Daily Law

One question. Every opinion. Every morning.

A new halakhic question and the full spectrum of rabbinic thought, delivered daily.