Talking to kids about a child with special needs - Is there a right age?

I recently attended a social event with Tuhina. The hosts and the other guests were meeting Tuhina for the first time and so I was prepared to come across questions about her. Almost 90% of these questions came from children who were mostly her age and were trying to figure out why she would not play with them. My hostess, trying to play it down tried to explain the kids that she is shy and needs more time, as she thought that the six year olds would not understand her being special needs child. This got me thinking when is the right age or right time to tell a child in the family, extended family or community about a child having different needs and abilities. Should we wait for a child to be an age where we feel he would understand or should we tell even a 3 year old who shows interest in the child, in the simplest way we can.

Since a long time, after I have come to terms with Tuhina's diagnosis, I have always felt better when people ask me about her and I am able to tell them in a way that they can comprehend. It gives me a satisfaction that they are trying to understand her and not making their own conclusions. And  I try to follow the same approach with children. I cannot say how I would have handled this scenario if Tuhina had a sibling, but she has a younger cousin who spends a lot of time with her. Children in the family instinctively know that their brother/sister is different but they still have questions. I feel more comfortable telling her cousin that his didi has different needs and its ok. She may not be able to do things the same way as him even as she grows up but she is doing the best she can.

Coming back to the party scene, kids are an inquisitive lot. So once the adults could successfully dodge their initial question of 'why she is not playing with them?' they came back with more after a while and I spent the next hour answering their queries. Some of the questions were quite intelligent -'if she doesnt speak how does she tell you when she needs water?' 'how is she able to tell with pictures?', 'will she understand me if i talk really slow and look into her eyes?', and she did try to make a conversation in slow 2 word sentences :). In those moments I felt that the kids were really trying to understand and include her and even if they didn't get all of it now, I know that eventually they will, more than many adults of our generation.