I think I last fired my J-frame when there was still snow in the shadows of the juniper trees.
So... May?
Prior to that, it saw 78 rounds in about a year.
I don't think it will be shot again until February or March.
So, almost 3 rounds per month, averaged over 27 months.
Edit: I nailed down the exact date. It was February 12th, 2012.
So, it will probably go more than 12 months, without being fired. (But the average remains the same.)