How long after a gall bladder removal does it take for pancreatic inflammation to go away?

Depends on severity. I assume that you developed biliary pancreatitis, i.e. Pancreatitis due to passage of a gallstone. Taking the gallbladder out reduces the risk of recurrent episodes of acute pancreatitis, but does not speed up resolution of the initial attack. Therefore the timing for resolution depends on the severity of the initial episode and the degree of damage. This may be weeks to months - follow with gi.