Temporary care?

Hi! I made a previous post about momma cat in this situation. She's currently at the vet for pyometra, so we will be bottle-feeding the kittens.

They're 3 days old now, and I was wondering if we should be feeding them strictly every 2 hours, even if they're sleeping peacefully? They've been fed a few times already and I was wondering if we have to wake them up mid sleep to feed them.