When one puts on tallis and tefillin BEFORE the correct time (ie. in the winter) do the same halachos apply as usual?
Can one talk in between the shel yad and shel rosh?
Does one have to do “atifah”?
Can one put them on in reverse order?
For a tallis there is no need for atifah, because there no mitzvah is fulfilled at the time of putting on the tallis. Later on, when the berachah is made over the tallis (after the correct time is reached), atifah should be performed.
For the tefillin, the halachah is that the mitzvah of tefillin applies even at night, but it is forbidden to wear tefillin at night. Under certain circumstances it is permitted to wear tefillin early (see Shulchan Aruch 30:3; Mishnah Berurah 13), and the mitzvah of tefillin is fulfilled.
Although the berachah for tefillin is not recited under these circumstances (until later), one should therefore not interrupt between the two tefillin (because it is possible that the interruption is not only on account of the berachah, but also essentially on account of interrupting between the two parts of the mitzvah), and certainly one should lay the arm tefillin before the head tefillin.