When Its Time to Tell
Of course, much depends upon the personality of the child and how the Santa myth has been handled up to this point. (We encourage parents to make it more of a game than a "fact", but we work with what is there.) This is one of the best scenarios that we have found so far: Published on FaceBook in 2016, by Charity Hutchinson:
https://www.washingtonpost.com/news/inspired-life/wp/2016/12/19/the-story-behind-the-beautiful-way-this-mom-told-her-sons-the-truth-about-santa/?utm_term=.f85c181003fd
https://www.today.com/parents/santa-real-handling-santa-talk-your-kids-t105765
https://www.washingtonpost.com/news/inspired-life/wp/2016/12/19/the-story-behind-the-beautiful-way-this-mom-told-her-sons-the-truth-about-santa/?utm_term=.f85c181003fd
https://www.today.com/parents/santa-real-handling-santa-talk-your-kids-t105765