it all depends on the dog itself, how mature is it, how well bred is it, condition etc, what has it been like on its previous foxes.
i like to give them a few doubled up when starting them, but i suppose i start them a bit early depending on how old they are when the season comes around.
yours should be perfect to start the season off with plenty of easy foxes (cubs) then let him have a few decent ones towards the back end of the season.
i have a young dog here that is getting everything single handed (when i go to ireland lamping) now, he's in the process of learning the knack at the mo,