Unless they were feral rescues that gorge themselves, most cats will regulate what they eat. Some become fat lazy cats - just keep an eye on your kitties and make sure they get lots of exercise.
We leave dry food out for them and they free feed. I have no idea how much food each of them eats. Our six cats go through a 4 pound bag of dry food approximately every 10 days.
We feed them wet food once a day. It's more of a supplement - or treat, really - than anything else. They get all the nutrition they need from the dry stuff. It's to encourage their moisture intake (though having plenty of fresh water around should suffice. Cats love "moving" water, so considering purchasing a drinking fountain is a good idea).
In fact, they weren't big lovers of wet food at first, so we only fed them what they would eat - which was splitting one pouch of wet food between two of them. When it's the wet stuff, we split one can three ways. Our kitties are adults - but they didn't eat much more when they were kittens - but we were feeding them the food labeled for kittens, so it was higher in protein.
At 8 months, they are still considered kittens, so they should be on a high protein kitten diet.