How long does it take before I start to notice some of the Radiesse in my cheeks start dissolving?

I would say the clinical improvement from Radiesse normally does not last more than a year.  There can be some decline beginning after a few months in some cases.  

Radiesse lasts anywhere from 6-12 months depending on the patient. I would be patient and your body will gradually resorb the product without complication.

Overcorrection can occur with Radiesse, and unlike the hyaluronic acid fillers, there is unfortunately no dissolving enzyme for calcium hydroxyapetite (the active ingredient in Radiesse). Intralesional steroid injections can be helpful sometimes for overcorrection and is a reasonable place to start. Merz notes this product can last up to 18 months, but in practice, I see the product begin to break down after 9-12 months. Swelling can last up to 2 weeks – 5 weeks seems a bit far out. Hope that helps!