You tube is great for seeing how things can be done. Casting jigs under a bobber is called float and fly, a technique used on crappie and small mouth bass. I use it allot especially in spring. I prefer slip floats due to the greater range of depth they can be fished. Float and fly allows you to maintain a given depth and have a slow retrieve allowing you to keep the lure in the strike zone longer. Casting and swimming jigs works well also and is another technique that I use especially this time of year it allows you to let the lure fall through the fish or swim it along through them. As you said the count down method will help you get to the level you want to fish at. I use 1 second equals 1 foot on a 1/32 jig as a given but a bulkier body could slow that down. Hope this helps a little.