Siman 657
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 קָטָן הַיּוֹדֵעַ לְנַעְנֵעַ לוּלָב כְּדִינוֹ, אָבִיו חַיָּב לִקְנוֹת לוֹ לוּלָב כְּדֵי לְחַנְּכוֹ בְּמִצְווֹת.
1 If a child knows how to shake the lulav properly, his father is obligated to buy him a lulav in order to educate him about the mitzvahs.