Hello! Welcome to BYC!! I would think putting primer on the concrete floor would be a waste. Between the chickens scratching around and you scraping poop off the floor and cleaning, wouldn't it peel off? I have concrete floors in two coops and they are unfinished, but I suppose there could be a difference yours and mine.
Welcome to BYC @Mucky_Ducky! - I'm the crazy guy with the waterer-video from YouTube!
I bet you will have a lot of fun here and there are good people with a ton of experiences willing to share their knowledge. Just ask!