If you are diligent on turning the heaters on when needed you probably will not have any problem. If they are working right you probably will not have to rake snow off. You can see if they are working when you turn them on they will show the track where the wires are installed. I think you are doing the right thing by waiting to see if they are working and taking care fo the roof & gutters in the summer. It will give you a chance to store some scratch for the job.