I think so too. I'm not an expert with the tiny ones, and I agree that article didn't really pin it down. Let me check one other source.
I guess i will just try my best and see. They can’t get out of the nesting box yet (8in or so tall). I’ve shown them the litter box but they climb right outSorry for the double post, The website the kitten lady says to introduce them to the litterbox at three weeks. It looks to me as though it's dependent on what stage the kittens themselves are at