Scans show my gallbladder is only functioning at 19%. how long can i wait before immediate surgery is required?

Based on symtpoms: I think you are referring to your gall bladder ejection fraction. A normal gb ef is between 35-75%. This is the amount of bile stored in the gb that is released after meal to digest fat. This problem can cause nausea, abdominal pain, and can mimic acute gallbladder disease from stones. Without significant symptoms I do not think there is an emergent situation.

Chances of this : Condition progressing to acute cholecystitis is small, but not zero. If you are having symptoms of gallbladder problem, such as post prandial pain, best solution is elective surgical cholecystectomy, before any emergency intervenes. Consult with your surgeon regarding optimal timing.