I change mine when I notice they are clear. I don’t wait 'til they turn dark. I think I left some in the microwave oven too long, and I think they are now permanently dark, even though they still seem to be working.
For drying them I put them into the microwave for 1 to 4 minutes, depending on how much I am drying. I repeat until the color is coming back. Then I put them in an open jar on top of a 176F coffee warmer. I put a paper towel over the opening, with a cheap temp/humidly sensor and leave it cooking 'til the humidity sensor is down to 10% (as low as it knows how to go.
I try to keep my AMSs at 10% as recorded in the front panel of my X1C, under the filament page. I change desiccants when the AMSs are still under 20%. I even keep the printer room at 40% with a dehumidifier. I have to empty it 1ce or 2ce per day. The one in the kitchen is bigger, so lasts 2 or 3 days… depending on the humidity outside getting in.