Found your post, had goats love goats... done all from raising them milking them and helping with the birthing process... nothing like a bottle of nice cool goats milk in the fridge way better than store bought... Your right about your young billy they can start breeding at a very young age... your doe is a nice size doe don't be surprised if she has more than one kid.
One thing you may want to do is familiarize yourself on what to do in case of birthing problems, how to recognize when the doe is in distress and what and how to correct birthing problems, not saying you will have any but being prepared is always good and vets can't always get their in time.
I have also began writing of my adventures on the farm at the moment its just a few funny adventures but I think I may delve deeper into farm life in future posts if they can help others.
upvoted and resteemed