When to stop stimulating?

I was wondering when I should stop stimulating the kittens to go to the bathroom? They are 4 weeks and 2 days old today. On kitten-rescue.com it says to start introduing the litterbox at 4 weeks and then it says they'll have "accidents" and such, but it never says whther or not I should continue stimulating.

Anyone know?

You can stop now and there will definitely be accidents...they should cleaning up after themselves now

Woohoo! No more butt rubbing!

They WERE learning to lick themseves, but then I took in an adult female kitty and she's doing it all fot them. Spoiled brats! It's ok, she'll be going to her new home next week so I can get back to training them, lol.