Well, you should wait at least 48 hours after feeding to handle them. But from the sounds of your post, you don't mean "pick them up and handle them" so much as you mean just doing cage maintenance type stuff. That should be ok.

It does sound like these snakes are brand new to your collection. I'd say the "aggression" is probably not that at all, but just a lack of security caused by the new surroundings. Give them more time to settle in and they will probably be fine.

Of course, snakes are still wild animals that can have unexpected reactions at times. One hiss and strike does not a mean snake make.