you have the general idea but you need to soak it down a bit. If this ceiling is stippled with a textur gun wich is more than likely lay the pastic on the floor ect. and mist the ceiling with some water from a hose if you like, it will take a fear bit of water so you would be there forever if you were to us a spray bottle. Then scrap it of it will take very little effort. It sould all ready have a stain blocker primer on it so you would only need to spot prime but that is up to you. Wash the ceiling with t.s.p rinse and rock on. have fun it is not hard work at all 2 people can normally do a 1200 sq foot house in 4to 6 hours keep in mind the plastic will be heavy so use soom caution with the water.