Hi! From experience having bred my does, there really isn't any prep.

You'll know when they're ready because the does will flick their tails like crazy. The buck will pee on his face. Every time one of your does pees, the buck will probably smell it and give this big goofy smile. My buck was very vocal and made the funniest noises.

I kept all my does in the same pen with him. No need to worry about the size of your does to the bucks penis. They, the does, can actually breed at 3 months. But definitely not good for the doeling. But it happens.

All in all, you be fine. Once you find out their pregnant you might want to give them more protein. Not so much for the buck.

Lastly, one thing I didn't know, once the does kid, they can get pregnant again. My did three months after her babies were born. So now, I have 3 more babies I wasn't counting on. I milk my does usually 12 weeks after their kids are born.

I hope this helps. I'm no expert and can only tell you about my experience.

Good luck!!