For Stark and I, it was the day he passed his Temperament Test.
Working with a reactive dog, especially a dog who is reactive to people, this was a huge deal for us. It took me a good year, maybe even two years to really get this under control.
I completely trust him with strangers now, and most kids but am still slightly watchful/selective in who I allow him to interact with. I don't want any regressing so we manage who gets to meet and play and interact with him.
The day he took the TT, and was at ease waiting his turn, and how much fun he looked like he had while actually doing the test.. that was the moment that stood out to me.
The crowd closing in on us - this was a huge one, since he had issues with people coming at him.