How long after a piercing will i drool excessively?

Not sure why you're drooling... If you're having difficulty swallowing and the saliva is just collecting in your mouth, go see your piercer. You may just be swelling a lot if its an oral piercing but it shouldnt be that bad. If its your lip, tongue or anything else around your mouth, try sucking on ice or just holding cold water in your mouth to help with swelling. If that doesnt help, just go see your piercer.