there is NO wrong time to use worm harnesses,just vary the presentations at certain times of the year!! i use them in spring,summer fall...all the time,many,many times they will catch fish when nothing else will..time & time again,vary the blade size,the speed,the leader lenght,the weight or the bait,i also will use minnows on them leetches...as well as big dew worms....it is the most versitile live bait presenting lure of all time...and it sends out vibrations that drive fish crazy!!! i have caught everything from walleyes to sturgeon,big channel cats and of course muskies and pike go CRAZY for them....it never ends use them right away on the opener i am...