Siman 641
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 הָעוֹשֶׂה סֻכָּה, בֵּין לְעַצְמוֹ בֵּין לְאַחֵר, אֵינוֹ מְבָרֵךְ עַל עֲשִׂיָּתָהּ אֲבָל שֶׁהֶחֱיָנוּ הָיָה רָאוּי לְבָרֵךְ כְּשֶׁעוֹשֶׂה אוֹתָהּ לְעַצְמוֹ, אֶלָּא שֶׁאָנוּ סוֹמְכִים עַל זְמַן שֶׁאָנוּ אוֹמְרִים עַל הַכּוֹס שֶׁל קִדּוּשׁ. הַגָּה: וְאִם לֹא אָכַל לַיְלָה רִאשׁוֹנָה בַּסֻּכָּה, אַף עַל פִּי שֶׁבֵּרַךְ זְמַן בְּבֵיתוֹ, כְּשֶׁאוֹכֵל בַּסֻּכָּה צָרִיךְ לְבָרֵךְ זְמַן מִשּׁוּם הַסֻּכָּה; וְאִם בֵּרַךְ זְמַן בִּשְׁעַת עֲשִׂיָהּ, סַגֵּי לֵיהּ. (רַ"ן פֶּרֶק לוּלָב וַעֲרָבָה).
1 The Blessing Shehecheyanu is Not Recited over the Construction of a Sukkah: One who constructs a sukkah, whether for himself or for someone else, does not make a blessing upon its construction. Shehecheyanu is appropriate to be said when one constructs a sukkah for himself. However, we rely on the blessing Shehecheyanu that we recite during Kiddush on the [first] night of Yom-Tov that [is recited] because of the mitzvah of sanctifying the festival, which is also a mitzvah that comes [only] periodically. (The one blessing covers both requirements). Rema: If one does not eat in the sukkah on the first night, even though he sanctifies the festival in his house, when he does eat in the sukkah he must sanctify the festival due to the sukkah. If he sanctifies the festival at the time of construction of the sukkah, it is sufficient for him [R"an].