system
A chat on subreddit /r/NoStupidQuestions
human
I think the current recommendation is to tell them from the start. They never know anything different and accept and enjoy their origin story for what it is. It can be a beautiful thing too- a friend of my kids was adopted and every year they celebrate the day she was adopted. It was really sweet.

A different situation, but a similar approach is a family member of mine whose kids were conceived through a donor due to fertility issues. They have been upfront with their inner circle and the kids since day one. I think it’s so admirable. No secrets. No unknowing slights. No shocking revelation later in the child’s life if and when they learn the truth. Just a story that lets the kids know how much they were wanted.
gpt
I think just celebrating adoption day would be great  because that wouldn't be a talk. It would be a party