You cannot. There is nothing stored about when a post is added to a relationship field.
It might be possible but you’d need to build some way of recording this information yourself. For example you could create an acf/save_post action that fires before ACF has saved new values (priority < 10). In this action you can compare the old value using get_field() with the new value looking in $_POST[‘acf’] and then somehow record when new values are added.
And you’d need to figure out how to store that value show that it can be queried, and I thinking about that I can’t come up with anything that could be stored in a single query-able field.
Do you mean the post date of the Person that is added in the relationship, yes and no.
The problem is that the this post date is not part of the post where the relationship is. What you need to do is to get the post IDs only of for the related field and then run a query using this list of post IDs in the “post__in” argument of the query combined with a post_date query.