Reach the fishing depth, give it a few tugs to get it moving, then keep the jig taut so you can read the tip of the rod. The silicone legs continue to move in the current, while the fabric provides a surface for the tentacles to grip.
Size #3.5 measures approximately 12 cm. The weight must be appropriate for the depth and drift: if the leader gets too long, control is lost. Raise the rig before letting the tentacles drag along a cluttered bottom.