I agree by 6 months your at or near the time I’d try too dependent of factors like if you do get them started to you have somewhere you can currently get them more tracks once home? I live in an area where typically now there’s deep crusty snow and the rabbits are pretty hard to come by especially for fresh started pups.
If this is the situation I’d wait to start for about a month when I’d expect better conditions. last year 2019 I was soloing a dog on Christmas morning early. Had a pup out just running around playing to associate her. Suddenly I heard screaming, she opened and was running w older dog.Within 3 days she was running w 2 other dogs, be careful here. She was 5 months old. By 7 months old she had dead rabbits under her. Imo that’s not real typical very often.
My buddy’s pup was in yard just a couple nights ago. A rabbit was in it too, he had no idea until dog opened and he saw rabbit. It’s about 5 months old now. Imo once they start I’d be busy trying to gain exposure. Tough or not he ought to try to find spots to work this pup.
Ive seen a pup one time start and actually track a little at 9 weeks old in my old pen believe it or not. I don’t recommend that. Dog blew up before a year old. Let it be a pup that young.
On the other hand more than one guy has been frustrated by 8-9 month old dogs or even older only wanted to play and chew sticks. Every dog can be different.
Another note regarding pens and this time of year. Things can be pretty open. A beagle is a scent hound, not a sight hound. Make sure pen you pick if you do use one is thick enough.
Id personally be introducing them to the areas holding rabbits by now