it all depends what you see happening in the future?
will you want any offspring from this hob, if not then as long as he is over 6 months old, get the snip done on him (not castration) as some vets may advise, as a castrated hob will not bring your jills out of season, then once he's over his op, and firing blanks he can live constantly with the jills, bringing them out of season, if at any time you wish to breed, borrow an entire hob for that particular jill,