True talcum powder is just powdered talc—essentially inert. The only way it could serve as an accelerant is as a nucleation site for the CA. Might happen. However, it is very difficult to find talcum powder that contains much, if any, talc. Most of them are cornstarch, these days. Not sure what cornstarch would do. Might work as a thickening agent.
You can use baking soda (sodium bicarbonate) as a filler/accelerator. However, the bicarb remains soluble and hydrophilic—it will eventually give you some very interesting, frothy areas on your model, unless you live in the middle to Death Valley or the Gobi Desert. (I found this out the hard way—a T-rex with a bad case of the creeping awfuls! )