That's a lot of roo for 12 girls. They'll be miserable with all the advances all day long. As a chicken owner myself may I suggest picking out two roos for the stock pot. 1:12 is a good ratio for flock health and well being.
"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht
I agree with James. For a week it might be teenage flirtations and awkward crowing. But pretty soon it will be the hens running ragged as they get jumped over and over.
My experience has been that 3 roos keep each other mostly busy and the hens get a lot more free time. Regardless of how it goes, I'm pretty sure I can identify and rectify issues. I am very familiar with helping roos transition to the pot phase.
A piece of land is worth as much as the person farming it.
-Le Livre du Colon, 1902