Question: It is too late for my daughter to hear havdala on motzaei Shabbos. Should she say it on Sunday?
Answer: Parents have a mitzva derabanan of chinuch, to train their children to observe mitzvos. Thus, the Mishna Berura (343:3) writes that when a child is old enough to appreciate what is permitted and forbidden on Shabbos, they should listen to kiddush and havdala.
The Shulchan Aruch (OC 299:6) writes that if one didn’t hear havdala on motzaei Shabbos, then one can do so until Tuesday. One saying havdala late should omit the berachos on ner and besamim.
While the Tur (OC 299) writes that one should recite havdala before eating anything (See Rema OC 299:6), the Mishna Berura (269:1) writes that we shouldn’t keep children waiting until after Kiddush to eat. Likewise, they may eat even before hearing havdala.
R’ Yehoshua Neuwirth (Chinuch Habanim Lemitzvos 24) writes that when Shabbos ends too late for children to stay up to hear havdala, they should recite it on Sunday morning, without the berachos on ner and besamim.
While some schools encourage their students to say the full havdala complete with the berachos on ner and besamim, this is an incorrect practice as havdala is never performed that way when performed late.