What are the chances

Very good chance. My first buck started breeding at 6 months old.....actually my new little guy bred 2 does on his great escape at 5 months ......kinda excited since I wasn't gonna use him till next breeding

Oh good!! I hate for my Nubian to not get bred! I was thinking of breeding her with a different buck but I really want registered Nubian kids

He should be plenty fertile. My buck was 5 months old when he covered my herd of does. All settled on the first breeding. Last year I had a 8 month old buck, all settled
Bucks are normally fertile at 3 months, so any older than that should be good.

Yep, he will be able.