You dont wait till your dishes are dirty before you wash them, same
I use the diaper method, change it
After a while one can predict when a new wick is needed. I dont wait till it's all gunked and really nasty. There is just a tiny drop in flavor, which tells me this is the right time, so one needs to be sensitive to this. Now my wife cannot make this detection and vapes it till it's like burnt sugar...I usually get 3 meals before I have to wash my dishes
Haha!