I haven't collected seed from my Calycanthus yet, but a general rule of thumb is that if a pod is cracked and opening, the seeds are suitable for storage. Just keep them dry and cool.

I read recently that this seed needs cold stratification, so you might consider sowing them in a milk jug now and setting them out to do their freeze/thaw cycle. Then they should sprout in the spring when they get good and ready.

Check out the Winter Sowing forum if you haven't already. You'll find info about preparing the milk jug, etc. This method is the only way to go for tree and shrub germination. See you there.

Here is a link that might be useful: Winter Sowing Forum