OK, that I know of anyways
Ali knew I was so excited to do my TTD and she really really wanted to do one too, so we let her! She was my Maid of Honor at our BFW and she is 9, so needless to say there were just a few stains on her dress after that night that wouldn't be coming out any time soon anyways, SO, why not? In preparation, we let her wear the dress to dinner a few times in Mexico, and we had her wear it to the wedding there as well, that way she could say she already wore it a bunch so no big deal.
Ali had SO much fun, we did it at the pool at the hotel at about 830am our last morning there.
Like many of us TTD'ers, the dress came out cleaner than it went in, so I think after we have it cleaned it will be good as new.
Enjoy!