The advantage of getting older animals is obviously the ability to breed them sooner, whatever you get they are a joy to rear & watch them grow. once they get past their baby skittish phase they are some of the most impressive, curious & confident snakes around.
Most importantly is to get as unrelated a pair as possible so if you can get lineage info all the better. Apparently there are a lot of in bred Easterns in the hobby so shop around for unrelated stock. Otherwise good luck & enjoy your new snakes, you will not be disappointed. They are awesome!

Andy.