Actually, according to Torah law, one is not required to recite the Parashat Tzitzit, the third parasha of Kri’at Shema, at all. It is one way to fulfill the mitzva of mentioning yetzi’at Mitzrayim[2] daily,[3] but this can also be accomplished in other ways[4] and, ostensibly, at different times.
However, the gemara[5] 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 a chance to first daven or recite Kri’at Shema. In the midst of his lectures, he would cover his face and recite the first pasuk of Kri’at Shema in order to fulfill the mitzva of Kri’at Shema in an abbreviated manner without disturbing his teaching. The gemara continues that he also would teach a halacha in which he could mention yetziat Mitzrayim “at its time” – that is, the time of Kri’at Shema.[6] This seems to indicate that mentioning yetzi’at Mitzrayim, which we fulfill with Parashat Tzitzit, should also be done before sof z’man Kri’at Shema.
However, there are also indications that one does not have to recite Parashat Tzitzit before sof z’man Kri’at Shema. For example, during the parts of the tefilla before P’sukei D’Zimra in the beginning of Shacharit, we recite the first pasuk of Shema.[7] The Rama[8] recommends the minhag to say, “Baruch shem k’vod …” following the pasuk, as usual. This indicates our interest that it serve as a fulfillment of Kri’at Shema, which is worthwhile since sof z’man Kri’at Shema sometimes passes before we reach Kri’at Shema in the davening.[9] Notably, this arrangement does not cover the requirement to mention yetziat Mitzrayim.[10] We must note, however, that this is what is advised in order to deal with the chance that one will miss sof z’man Kri’at Shema. When one expects to miss it, he should say all three parshiyot of Shema before the end-time of Kri’at Shema comes.[11]
Interestingly, although there are different sources for reading each of the three parshiyot, the Rambam[12] discusses them as one unit, which is compatible with the mishna[13] that explains the order of these parshiyot. The Bi’ur Halacha[14] similarly posits that even if one recites the three parshiyot when they are not sandwiched between the birchot Kri’at Shema, he should not speak even between the parshiyot.
Fulfilling the mitzva of Kri’at Shema at its time by reciting it before davening is less than a perfect solution for several reasons, some of which can be remedied by waking up a little earlier. It is not ideal that when one recites Kri’at Shema in its normal place in davening, before Shemoneh Esrei, he is not simultaneously fulfilling the mitzva of Kri’at Shema,[15] and certainly if it is too late at that point to do so. Also, it is generally problematic to recite the full text of Kri’at Shema, which includes a reference to tefillin, without having tefillin on,[16] and this is usually the case for those who recite a last-minute Kri’at Shema. If, however, one is unable to both put on tefillin and make it to Kri’at Shema on time, he can recite Kri’at Shema anyway.[17] Therefore, if one is able to start davening before sof z’man Kri’at Shema but will not get to Kri’at Shema on time, he should make the effort to at least put on tefillin before reciting Kri’at Shema.
Another matter to consider is Birkat HaTorah. One may not learn before saying Birkat HaTorah, and it is debatable whether reciting Kri’at Shema in order to fulfill that mitzva is tantamount to learning.[18] It is thus preferable to say Birkat HaTorah beforehand.