My guess is every 6 months, but keep Wampa static. It's a wild guess, but CG seems to like to work in groups of 30 shards.
It'll be interesting to see what toons they rotate in. I thought it odd they put OG Han in there, but i guess its to makeup for the low shard rewards relative to GK and Traya (i.e., if you finish in the bottom 10 you get just 1 shard).
side note, I think it's funny that people have to post they're not advocating for pitchforks when inquiring. I'm glad you did it, but it's still funny to me.