STARTING SIX MONTHS OLD PUPPIES IN A PEN IS A GOOD IDEA.IF THE PUPPIES START EARLY AND RUN WITH OLDERS PUPPIES YOU MAY WANT TO LIMIT THEIR RUNNING TIME AS THEIR BONES AND BODIES ARE STILL DEVELOPING .A LOT OF PEOPLE RUINED REAL GOOD PUPPIES OFF OF SHERIDANS DICEMAN AND OTHER BREEDS BECAUSE THEY STARTED EARLY AND WAS FAST BY TRYING TO RUN THEM WITH OLDER PUPPIES AND GROWN DOGS .AS THE PUPPIES GET OLDER RUN THEM A LITTLE LONGER EACH TIME YOU TAKE THEM .AS FOR OUTSIDE ,THE PUPPIES WOULD PROBABLY NEED TO BE A LITTLE OLDER ,POSSIBILY SEVEN OR EIGHT MONTHS OLD BECAUSE OF MATURITY.CHECK WITH OLDER OUTSIDE HUNTERS FOR THEIR VIEWS ON THIS SUBJECT.BUT MAINLY,PUT THEM IN THE WOODS AS MUCH AS POSSIBLE BEFORE THEY ARE A YEAR OLD .WEIGH THEIR GOOD POINTS AND THEIR BAD POINTS.REMEMBER MOST OF THE TIME,NOT ALWAYS,A FEMALE WILL MATURE QUICKER THAN A MALE. HAPPY HUNTING.