Emperor Moth eggs hatched this morning - advice

[Yashca]

My Emperor Moth eggs hatched this morning, and I moved them into a tupperware container with bramble leaves for foodplant.

As of yet, most of the caterpillars are just stood about on the leaves. There has been a little bit of eating from a few of the caterpillars at the edge of the leaves, but as of yet they have not been eating as much as I have expected.

Is this normal? Will they start to eat more soon, or is there something wrong?

Also, because I am feeding single bramble leaves at the moment, how often would you reccomend changing them for fresh?

Thanks, Yashca.