אֵלֶּה תוֹלְדוֹת הַשָּׁמַיִם וְהָאָרֶץ, בְּהִבָּרְאָם: בְּיוֹם, עֲשׂוֹת יְהוָה אֱלֹהִים--אֶרֶץ וְשָׁמָיִם
This has two sentences in one verse. The second is slightly ill-formed. Moreover, the first sentence announces something that is not coming up. Rather, what is announced was edited out, by the priestly editor. The original version must have been:אֵלֶּה תוֹלְדוֹת הַשָּׁמַיִם וְהָאָרֶץ, בְּהִבָּרְאָם: בְּרֵאשִׁית, בָּרָא אֱלֹהִים, אֵת הַשָּׁמַיִם, וְאֵת הָאָרֶץ. וְהָאָרֶץ, הָיְתָה תֹהוּ וָבֹהוּ, וְחֹשֶׁךְ, עַל-פְּנֵי תְהוֹם; וְרוּחַ אֱלֹהִים, מְרַחֶפֶת עַל-פְּנֵי הַמָּיִם. וַיֹּאמֶר אֱלֹהִים, יְהִי אוֹר; וַיְהִי-אוֹר. וַיַּרְא אֱלֹהִים אֶת-הָאוֹר, כִּי-טוֹב; וַיַּבְדֵּל אֱלֹהִים, בֵּין הָאוֹר וּבֵין הַחֹשֶׁךְ. וַיִּקְרָא אֱלֹהִים לָאוֹר יוֹם, וְלַחֹשֶׁךְ קָרָא לָיְלָה; וַיְהִי-עֶרֶב וַיְהִי-בֹקֶר, יוֹם אֶחָד. וַיְכֻלּוּ הַשָּׁמַיִם וְהָאָרֶץ, וְכָל-צְבָאָם, בְּיוֹם, עֲשׂוֹת יְהוָה אֱלֹהִים--אֶרֶץ וְשָׁמָיִם:
The priestly editor changed things around to have Creation last seven days. But it still says Yom Echad, not Yom Rishon. The editor felt free to insert, to reorder, not to change the wording of authorative text. Also, the editor left a mark, the letter ה in בְּהִבָּרְאָם is written smaller. The above is the beginning of the Torah, לעניות דעתי, L'Aniut Da'ati, prior to the priestly revolution.