How to use roof/gutter de-icing system? My house came beside one and I'm not entirely sure how to...

My house came beside one and I'm not entirely sure how to use it. I turned it on two days ago because we had several days of rainfall followed by below freezing temperatures. Is it something I should hold switched on in winter or of late turn on when I see wet gutters and the heat is near or below freezing?
Need assist roasting!!?
Answers:    Ours have been on since only just after Thanksgiving, but then, we own had an indecent amount of snow this winter. Ordinarily, we unplug it when the snow isn't too wide on the roof.
I want to acquire a tankless marine oven....
It is intended to melt rime so that the ice won't freeze final up under your shingles. If the rime does that you run the risk of getting lots of water wounded from the roof. If you see ice on the roof turn it on to thaw the ice away.