Chris, your best source of information on the subject is http://www.koiandponds.com/dry-fertilization.htm
I believe it is way to early to do it now, unless you have indoor or heated facilities. One cold front after they have hatched, and you loose all your fry.
Live food is also not readily available at the moment. I would wait at least until end of September.
You can now almost start to prepare breeding of some Daphnia or Brine Shrimp so that you have a life food source by the time the fry hatch.