Hello KPhil...
Are we cycling a tank? Prime works as soon as it's added to tap water. It removes chlorine and chloramine. These two chemicals the public water people put into the tap to make it safe for us to drink are toxic to aquarium fish.
If your tank is establish (cycled), then you already have bacteria to use the forms of nitrogen that are harmful to your fish. I don't see the need for the Dr. Tim's stuff.
B