What precautions to take with a pond that has no fish in it currently?

We purchased a property about a year back that has a pond and I was considering turning into a koi pond. To my knowledge there are currently no fish in the pond.

I have seen listings on ebay for koi fry and think that might be the best option to introduce? Would they be too small, any predators that would go after them?

I am located in New Jersey if it means anything.

Thanks in advance!