Siman 430
Presented here for study, not as a practical ruling. The Shulchan Aruch rules by Sephardi custom, the Rema's glosses by Ashkenazi custom, and the Kitzur follows Ashkenazi custom. For a practical question, ask your rabbi.
א שַׁבָּת שֶׁלִפְנֵי הַפֶסַח קוֹרִין אוֹתוֹ שַׁבָּת הַגָּדוֹל, מִפְנֵי הַנֵּס שֶׁנַּעשָׂה בּוֹ. הַגָּה: וְהַמִּנְהָג לוֹמַר בְּמִנְחָה הַהַגָּדָה, מִתְּחִלַּת עֲבָדִים הָיִינוּ עַד לְכַפֵּר עַל כָּל עֲוֹנוֹתֵינוּ; וּפוֹסְקִים לוֹמַר בָּרְכִי נַפְשִׁי (מִנְהָגִים).
1 Shabbos Hagadol The Shabbat before Passover is called "Shabbat HaGadol" because of the miracle that was performed. Rema: It's a custom at Mincha to recite the Haggadah from the section of Avadim Hayinu to L’chapeir al kol avonoseinu. And we stop saying "barcei nafshei".(Minhagim)