Last year I peeked in once per week and opened up the egg boxes. I was using substrateless incubation and they all hatched out perfect. I'll probably do the same thing this year just because I like watching the embryos inside develop and making sure all of the eggs are doing fine Wigglers!

I've read that you don't even have to circulate the air in the egg box at all. A good number of breeders just leave the egg box alone for 60 days.