Rava rules that mourning restrictions do not apply until the week of Tisha bAv (not from the New Moon), and the passage lists the specific prohibitions that apply on Tisha bAv itself: eating, drinking, anointing with oil, wearing shoes, and conjugal relations, as well as studying Torah, Prophets, Writings, Mishna, Gemara, midrash, halakhot, and aggadot.
אָמַר רָבָא: הֲלָכָה כְּרַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל. וְאָמַר רָבָא: הֲלָכָה כְּרַבִּי מֵאִיר. וְתַרְוַיְיהוּ לְקוּלָּא, וּצְרִיכָא. דְּאִי אַשְׁמוֹעִינַן הֲלָכָה כְּרַבִּי מֵאִיר, הֲוָה אָמֵינָא: אֲפִילּוּ מֵרֹאשׁ חֹדֶשׁ, קָמַשְׁמַע לַן הֲלָכָה כְּרַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל. תָּנוּ רַבָּנַן: כׇּל מִצְוֹת הַנּוֹהֲגוֹת בְּאָבֵל — נוֹהֲגוֹת בְּתִשְׁעָה בְּאָב; אָסוּר בַּאֲכִילָה וּבִשְׁתִיָּה, וּבְסִיכָה, וּבִנְעִילַת הַסַּנְדָּל, וּבְתַשְׁמִישׁ הַמִּטָּה. וְאָסוּר לִקְרוֹת בַּתּוֹרָה בַּנְּבִיאִים וּבַכְּתוּבִים, וְלִשְׁנוֹת בַּמִּשְׁנָה בַּתַּלְמוּד וּבַמִּדְרָשׁ וּבָהֲלָכוֹת וּבָאַגָּדוֹת.
With regard to the halakha itself, Rava said: The halakha is in accordance with the opinion of Rabban Shimon ben Gamliel. And Rava also said that the halakha is in accordance with the opinion of Rabbi Meir. The Gemara remarks: And both of these rulings are intended as a leniency. And it is necessary for Rava to state both rulings, for had he taught us only that the halakha is in accordance with the opinion of Rabbi Meir, I would have said that the mourning practices are obligatory even from the New Moon, as maintained by Rabbi Meir. Therefore, Rava teaches us that the halakha is in accordance with the opinion of Rabban Shimon ben Gamliel, that the restrictions of mourning do not apply until the week of the Ninth of Av. The Sages taught: All mitzvot practiced by a mourner are likewise practiced on the Ninth of Av: It is prohibited to engage in eating, and in drinking, and in smearing oil on one’s body, and in wearing shoes, and in conjugal relations. It is prohibited to read from the Torah, from the Prophets, and from the Writings, or to study from the Mishna, from the Gemara, and from midrash, and from collections of halakhot, and from collections of aggadot.