I am praying Shacharit with no Minyan, at least at the beginning of the prayer. must we recite "Rabbi Yishmael..." since we cannot yet say Kaddish De Rabbanan? We do say this kaddish later after a minyan is formed, though.

Shalom, Thank you for your question. Firstly let me direct you to ask your question to the Rabbi of the shule you are praying in, as he will be much more knowledgeable about local customs. However if there isn’t a Rabbi (whose answer would certainly be more binding than anything I could write here from a distance), then permit me to answer your query. The section of "Rabbi Yishmael" which lists his 13 principles of how Torah is derived, is said as part of the morning blessings and the readings of the offerings. It plays an important part in the structure of the prayer service. After saying the offerings, we then say a chapter of Mishna (Ezeh'hu Mekoman …) from the tractate of Zevachim, and follow it with the section from the Sifra (a Rabbinic Midrash) - "Rabbi Yishmael". By saying these three sections one merits to learn from the written Torah, then the Mishna, and then the section "Rabbi Yishmael" which is Rabbinic Midrash that equates to, and talks about, the Gemara. There is special importance to learning from all these three sections of Torah. All this has importance whether or not there is a minyan to say kaddish. The kaddish is said after the learning – but the learning is important irrespective of the ability to say kaddish. That being so, you should say the section "Rabbi Yishmael" whether there is a minyan or not – and you can continue your practice of saying a kaddish de'rabanan when a minyan gathers after reciting some more words of Torah leaning. Blessings.