48–72 hours. If you are better in 24 hours or less you probably should not be on antibiotics.
I agree chlorespectic spray, you can spray much more often then it says I have no idea what it says, but I have taken it by the teaspoon full for esophogeal ulcers under doctor recommendations. Not that I am telling you to take it by the teaspoon full, just spray it at your throat.
Also, no hot liquids! Cool and cold. People many times recommend tea and soup, bu tthat is for solds, not for strep. Remember heat causes inflammation. Suck on a popsickle. Think about it, who ever heard of a kid getting a hot cocoa for his sore throat after a tonsilectomy? The cold will reduce inflammation.
Also, take a couple of tylenol maybe.