Certified GKH Gardening Expert
This will take much more than a day to do its job. I would expect 1 to 3 weeks to start seeing recovery. It can help with fungal spotting, but if the spotting is severe, then it may need an antifungal.
This article will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
Although it can kill some pests, it is more to keep them away. If you want something that you can make at home for pests, this article will help: https://www.gardeningknowhow.com/special/organic/natural-home-pesticides-organic-garden-pest-control.htm