With a tooth infection how soon would your face swell if it was going to the only thing i can use is salt water rinse and peroxide mouthwash ?

Variable: If you have a true infection, you should be on antibiotics. You should find a health care professional who can examine you and prescribe one. There is no way to determine how quickly the infection will spread, especially without a medical history and a clinical and radiographic evaluation.

May not swell at all: Salt water rinses and peroxide will not treat your issue. You need to see a dentist who can treat the tooth in question and prescribe antibiotics. The sooner you seek treatment the sooner you will feel better. All the best...