New kit - intoduction question

Hey all, so we just picked up our 3rd chin (9 week old kit) and we're hoping to eventually pair him with our 1 year old chin. I've read up plenty on intro methods & procedures, but couldn't find any advice based on age; at what age would it be appropriate to start attempting an intro? I know the 6 month mark is a big one for kits as far as new freedoms, is this a recommended starting point? Or should I wait for him to get a bit bigger than that? Our 1 year old isn't very large, and has shown interest in our oldest chin (who's unfortunately a satisfied loner) but I know that it's still a roll of the dice as to whether the two will get along or not. Any input is appreciated! We're not trying to rush things, just curious.



P.S. here's his 'welcome home' photo op! (the plastic-bottom cage is getting swapped for a FN181 as soon as it gets delivered)