Brush-B-Gone is a very good product. My mom and sister still use it from time to time. The A/I is trichopyr and it begins involvement almost immediately assuming it is mixed properly for the plant or plants to be treated and that they are actively growing. However Trichopyr may take up to 3 weeks to demonstrate involvement because of its MOA,depending on the plant and its size at treatment and of course the rate of treatment, however I'm sure you know this from your Pest. training. If your looking for quicker results try a product line called Corona. Its available at most Lowes stores.