Anywhere from 20 to 30 minutes depending on your stuffing and if you are prep baking it for a time -- the oven temp varies from 325 to 450 degrees too, depending on your stuffing. This web site might help, it has several recipes and you might find one that is similar to yours.
http://www.cooks.com/rec/search/0,1-0,baked_stuffed_shrimp,FF.html

