There is an earliest time when one can put on tallit and tefillin - generally between 40 minutes and an hour before sunrise, depending on which posek one follows. What does one do if he has to daven much earlier than sunrise to the extent where he has to put on his tallit and tefillin before he is obligated to do so? This question is quite pertinent right now, as sunrise in Bergen County (where this blog is written) is well after 7am, and thus minyanim that begin closer to 6am begin before most poskim feel there is an obligation for tallit and tefillin.
Rav Moshe Feinstein felt that such a situation is comparable to a case of a person who gets tallit and tefillin in the middle of davening. In that case, the individual should put them on and make the bracha after ישתבח but before קדיש. In this case, since one has the tallit and tefillin from the start but is simply not yet obligated to wear them and, by extension, should not make the bracha, the person is allowed to put them on right away, but should wait until after ישתבח then pause and make the bracha.
There are those who say that in this case one should move his tallit and tefillin around before making the bracha so as to create circumstances as if he is newly putting them on at that time. This would be done to fulfill the requirement of עובר לעשייתן - that brachot made on mitzvot have to be made before the mitzva is performed. Rav Moshe felt that such movement was not necessary for the purposes of the bracha, and that the עובר לעשייתן requirement was fulfilled with the continued performance of the mitzva after the bracha is made. However, he does encourage one to move around his tallit and tefillin when he makes the bracha as a recognition of the mitzva that he is now making a bracha on.