Ned,
While I can to not cite the exact canon reference from the Pendalion, the canonical age for ordination for diaconate in the Orthodox Church is 25. For the priesthood it would be 30, and bishop would be 35. Though these are cited as the canonical age requirments for ordination, they are not strictly enforced. The closest I have seen in the enforcement for age requirement is that for bishop.
Given most educational requirements needed for ordination, most candidates approaching ordination are seldomly below the age of 25. I hope this helps.
In IC XC,
Father Anthony+
