the longer you wait to treat it...the worse it will get and the longer it will last.
try using the vaginal 7 night cream or calling your gyno dr. and ask them to perscribe you a diflucane. a pill taken once or twice and your symptoms should deminish within a day or two..
if it is due to taking antibiotics, try eating plain yogurt while taking the antibiotics...this will prevent a yeast infection from even begining.
hope this is some help to ya
there is not set amount of time