Time? Well, it depends. But generally I find that good improvement happens from 6 months onward, for my 9-11% abv meads. Higher abv will take longer.
Temperature? Defininately not the freezer! Wine cellar termperature? 50-55 degrees F I think is about right? I don't measure it, but I keep mine in the pump house in the summer, and a back room in the winter, and suspect it is generally in the 50-60 range. It works for me.