ive alway's been told a year or fifteen month's for hare's let them build strangth and healthy lung's ive seen dog's ruined becouse there ran to early or over worked but i suppose it depend's what you hunt and depend's on breed i would go for rabbit's then move on when dog is strong enough ive seen dog's dis hearted becouse they couldnt catch the hare but that's the owner's fault for being to eager and not careing about dog's just result's but i think training and exercise bring's result's good luck