well it depends. some guys i know it takes a day or two. for me it was bam one night brotha. i came off a dbol deca test cycle. could not bust for a long time it was horrible. proviron fixed it for me in one night. now other guys that have had this problem came to me and it took a day or two. its ok that you don't have it yet proviron is just a great additive. its not like you are starting deca without test or something. but at most a few days you'll notice it. you will start popping boners like its going out of style, you'll know. also your muslces will be considerable harder and you might notice more definition on your abs, dunno your bf but i did