I've met with my breeder numerous times and asked many questions and had many doberman related conversations. I didn't ask that question until just as I was getting ready to leave the last time I met them at a show.
I don't know if there's any ettiquete involved personally. For me, I knew I was going to be spending money on a puppy so it was the least important question. I was more interested in learning about her breeding program and the local doberman world. I don't personally think there's any one certain way you should ask that but just bring it in to the conversation as you feel comfortable doing so.
