Question:


Answer: The Torah does not require one to recite the third parasha of Kri’at Shema (Parashat Tzitzit) at all. It is one way to fulfill the mitzva of mentioning yetzi’at Mitzrayim (liberation from Egypt = yM) daily (see Berachot 12b), which can also be accomplished in other ways (see Berachot 21a) and, ostensibly, at different times.
However, the gemara (Berachot 13b) tells a story that complicates the matter. Rabbi Yehuda Hanasi would teach Torah publicly from early morning in a manner that did not give him an opportunity to first daven or recite Kri’at Shema. During his teaching, he would cover his face and recite the first pasuk of Kri’at Shema to fulfill Kri’at Shema in a minimalistic manner without disturbing his teaching. The gemara continues that he also would teach a halacha in which he could mention yM "at its time," i.e., the time of Kri’at Shema (Rashi, ad loc). So we seem to have an indication that mentioning yetzi’at Mitzrayim, which we fulfill with Parashat Tzitzit, should also be done before szKS.
On the other hand, there are indications that one does not have to recite Parashat Tzitzit before szKS. During the recitation of Korbanot in the beginning of Shacharit, we recite the first pasuk of Shema. The Rama (Orach Chayim 46:9) recommends the minhag to say "Baruch shem k’vod …" following the pasuk. This indicates our interest that it serve as a fulfillment of Kri’at Shema, since sometimes szKS passes before we reach Kri’at Shema in davening. Some recommend reciting the entire first parasha, as it might all be required for the Torah-level mitzva (Mishna Berura 46:31). There is no similar arrangement for mentioning yM (it is mentioned early in P’sukei D’Zimra- Shulchan Aruch Harav, OC 46:9). However, that is what is done to deal with the chance that one will miss szKS. When one expects to miss it, he should say all three parshiyot of Shema (Pri Chadash (OC 46:9), Chayei Adam (8:7), and Mishna Berura (46:31)). While Rabbi Yehuda Hanasi had a special reason to be minimalistic, we should do Kri’at Shema in as close to the rabbinically mandated manner as we can.
Interestingly, while there are different sources for reading each of the three parshiyot, the Rambam (Kri’at Shema 1:2) writes about them as one unit. The mishna (Berachot 13a), in discussing the order of the parshiyot, also seems to treat them as one unit. The Be’ur Halacha (66:5) infers from the Rashba that when reciting the three parshiyot without being sandwiched between birkot Kri’at Shema one should not speak even between the parshiyot.
Fulfilling Kri’at Shema at its time in this way is deficient in several ways, some of which can be remedied without waking up much earlier. It is not ideal when the Kri’at Shema one says before Shemoneh Esrei is not the one with which he is fulfilling the mitzva of Kri’at Shema (Mishna Berura 46:31), and certainly if it is too late to do so. One may not learn before saying Birkot HaTorah. It is debatable whether reciting Kri’at Shema to fulfill that mitzva(ot) counts as learning (see Rama, OC 46:9 and B’tzel Hachochma I, 1). It is thus preferable to say Birkot Hatorah beforehand. It is generally problematic to recite the full text of Kri’at Shema, including the words referring to tefillin without having them on (Berachot 14b). If one does not have time to put on tefillin and make it to Kri’at Shema on time, he can recite Kri’at Shema anyway (Mishna Berura 48:5; see Yechave Da’at VI, 2). Yet, it is preferable to do so while wearing tefillin. Therefore, if one is able to start davening before szKS but will not get to Kri’at Shema on time, he should put on the tefillin before reciting Kri’at Shema. (There is discussion whether one who is unsure whether he will get to Kri’at Shema on time can recite it first with a condition; this is beyond our present scope.)