usually for us we start casting harnesses a week or so after guys report that they are getting them trolling with harnesses. it might take a little bit of work to figure out the count down to find the suspended fish. if you can get a good drift to cover ground casting can be just as affective as trolling harnesses just have to make sure the drift isn't to fast right now the fish aren't to fast moving yet with the water temps still in the upper 40's, might be to much work to chase a "fast moving" worm.