First time was two years ago. I was third in line at Mad Taco for the 8 AM cask tap. Then it was released last year as part of the anniv party I think. I don't recall the third release, but @blisscent may be right.
you're right about the second release, i got it at the anniversary party last year. @blisscent is right too, Sean did a random batch in January of this year. all batches were incredible, i like it much more than double sunshine.