You have some experience with the hens, and if you are getting a straight run of chicks, there will be about half to a bit more than half generally speaking will be roosters. So you are going to have some to pick from.... Not quite sure where your finally numbers are for the flock next fall. One can get by with more birds, if the extra birds are chicks. Chicks are smaller and take up less space. Summer the days are long, and they spend more time outside of the coup, but as fall arrives, the chicks are now full grown, and you need to get your flock down to a size that can happily remain in the coup for nearly 14 hours a day of darkness.
so 12 + 45 / 2 (half hens, Half roos) so say 22 hens = 12 original + 22 new = 34 hens and pullets give or take, especially if you lose some or cull out of the older girls.
I would recommend butchering most of the 23 roosters, and probably putting them into their own pens away from the laying flock, rather earlier than later, 8 weeks or so...... Roosters raised together often times will work well together, but not always. Pick six, whittle it down to 3-4, then again to the final one or two roosters that you want with the flock. I think I would even put a pair in the flock, see how it goes, before I do the final culling.
Roosters will change the flock dynamics. With just hens, you are in the rooster position, as you bring them food, break up fights, prepare nests for them. The trick is to get a roo that will allow you to keep that position, where as he takes up the slack when you are not there. As the previous posters mentioned, you can get a wonderful rooster, or a nightmare, so don't be too quick with the last cull.
Mrs K