You need to help him to manage the meeting time.
You need to remind him early in the meeting that you have a hard stop at 5:30 to pick up your daughter. When it is about 5:20 and he is still talking, you need to ask if you need to schedule another meeting to finish the topic. When it is approaching 5:30 you need to collect your stuff and standing up while listening, so there is no surprise that you have to go. It takes a little practice to do this well, but this is typically what people do in this situation.
