Unfortunately the pests that can attack cabbage won't all be controlled by a single pesticide. Cabbage can be attacked by root maggots in the soil, and leaves may be eaten by caterpillars, flea beetles, aphids to name a few. The dust you mentioned contains a bacterium (Btk) that only works for caterpillars of moths and butterflies. The soap product needs to get a direct hit on a visible insect and works best on soft-bodied critters, so isn't so good for flea beetles and root maggots in the soil, and anything that gets between the leaves. Not every pest that goes for cabbage is necessarily going to find yours. For most of them I would wait and see and then identify the culprit. If it's the first time you've grown cabbage you might not have a problem unless you already grow other crucifers or you neighbors do. Otherwise you need to look for the best control for each individual cabbage pest that occurs in your area.
