I think as early as possible, so perhaps even in preschool we can start talking about identity in different ways.
Obviously, the way you explain this to a child in preschool would be quite different, but if you look at the books that are offered in day cares and in preschools, a lot of them are quite heteronormative and cisnormative, so a lot of times the examples that many of these teachers use are examples of families that have a mother and a father, and those are the only examples they have. For example, I have a child in preschool and the comments are really heteronormative, so if she makes friends with a little boy, all of a sudden that's her boyfriend, but if she's friends with a girl, that's her best friend.
I think that education piece can start very early because we're modelling that to really young children. Many LGBTQ2S books are available for children as young as preschool, and they're brilliant. I believe those books should be available in the school system.