YOu don't say so, but I'm reading between the lines that your 12 year old is interested in Greek mythology, probably from those Percy Jackson books. However, actual ancient sites are harder to appreciate without more backgrounding, and without a guide she may be disappointed at unexplained ruins. On a "road trip," places mentioned by u & others that she'll most easily appreicate would be the stadium at Ancient Nemea, Palamidi fortress & Nafplio's high Acronafplia ramparts, Epidaurus' amazing theatre.. Nafplio & its small museum (it has the world's only Iliad-era warrior armor!). I seldom disagree with "stanbr," but With your short time-frame, I suggest you not attempt to include Ancient Corinth; for one thing, ancient sites may be doing the off-season 3pm early closing.. and remember it's November & gets dark early. If forced to choose, I'd opt to keep driving over Canal, then stop for Ancient Nemea (less than an hour if u don't do museum), then head S. for Nafplio... You could at least explore Old Town before dark.
Monday 11/l3 looks like a looong day with major Backtracking... to Epidaurus, then BACK To Nafplio (and then there's lunch -- I'm thinking it would be 2 earliest before you got to Mycenae.... an over-reach?? Have you considered ANcient TIRYNS? It's right outside Nafplio, also an Iliad-era fortress, just not as spectacular, and not restored... but same gigantic boulder construction. https://hubpages.com/travel/palace-of-tiryns Can be explored in less than an hour. Even so... I'd be very leery of then heading delphi before dark. How are you at driving in fading light in the mountains? You might do better by another night in Nafplio, then an early start. Also -- carefully check the times/distance from Nafplio - Delphi -- going West vs backtracking to Corinth etc - the latter may actually be faster. And remember, you've never driving in Greece before, when many signs are in a different Alphabet.
If you do go to Delphi, its museum has excellent signage, but the site itself does this need interpretation, unless you've done serious study & have an excellent guidebook & print-outs. There's an excellent local-based licensed guide (these rigorously-educated guides are the only ones allowed to escort tourists onto ancient sites) - http://www.delphi-guide.gr/ However, it isn't cheap of course; 2020 rates were about €60 per hr, 2 hr minimum. A possible alternative (tho haven't personally tested it) would be an audio-guide for your smart phone. this offer combines it with an entry ticket - https://www.getyourguide.com/delphi-greece-l116/delphi-archaeological-site-and-museum-admission-ticket-t427238/
That being said, my inclination would be to "play it by ear"... see how it goes... I think you may decide not to rush away from NAfplio, and leave Delphi for a future trip.
