I'm so impatient that I couldn't stand not knowing if my two little Salvia cuttings were actually rooting or not. So... I gently pulled one out and "Woo hoo!" - it's rooting!!! They've only been in there for a week!
So my rooting medium must be okay after all - it's equal parts peat moss, crushed charcoal and sterilized (microwaved) potting soil. I tried to keep it really loose and on the drier side and have the cutting stuck in it inside of tall plastic feta cheese containers.