Feeding tiny White's treefrog-lets..

[spooky]

I'm hoping to get my white's on Thursday but not quite sure on feeding... Asked in pet shop and they suggested size 1 crickets, which I'm assuming are the smallest, but they still look too big to me. Would flightless fruit flies be a better option? And how much/how often would I need to feed the froglet/s? Can I just put a whole batch in and leave the frog/s to it? Or add a few every day/every other day? And do flies need to be fed with a powder supplement? Sorry for all the questions, I just want to make sure that I'm totally prepared for my frog/s!!