I have heard case as young as 6months old-coming into heat. And she will back up to a crate even & let him do it if she's ready. So seperating can be very hard. If you plan to get him fixed anyways I would do it right away. But if you do plan on breeding in the future I would be coming with a stronger game plan. Would you having a band on & your wife having panties on keep you from going at it if you really wanted to-it doesnt stop my husband
The first heat can be very light some people dont even know until its to late. My friend had a dog come in at 8 mons & again at 12, some come in more often & sooner-its just very unpredictable.