Absolutely possible. Growin up I had some Holstein bull calves that I bottle fed that I never cut. Being preoccupied with being a kid, I didn't get around to sellin them so my dad turned em out on grass with his commercial cows. He was certain these 11month old 'calves' weren't capable of breeding. Low and behold, next spring there were 2 black/white spotted calves.
12 month old bulls are good for breeding. Just bought a 12 month old bull and gonna use him on 10 cows. If the bull is 12 months only breed 12 cows, 15 months to 15 cows until he's atleast 20 months or so. You can get a whole extra breeding season out of the bull as long as you take care of him.