What is the Earliest Source? 6 - The Four Questions

When I posted this earlier, I was not so precise.

What is the earliest source stating that the Youngest Child should recite the 4 questions as prescribed in the Mishnah and the Haggadah?

Caveat, I do not mean to address the case when the child asks his/her own questions such as "Why do we pour a 2nd cup of wine?"

KT
RRW