when to introduce litter box

My kittens are 20 days old today and are not doing 'their business' by themselves, I have only seen 1 little poo-poo in the box 3 days ago and momma is still licking them to go. I thought by now they would be doing it themselves without moms help.
According to the kitten calendar I should be introducing litter today, do I need to when they don't seem to be doing anything? Or should I wait until I see evidence in their box?

I had newborns and if I remember correctly, they started using a litter box at around 4 weeks. 20 days might be a bit too young yet. I would keep putting the litter box near them so when their natural instinct to dig & bury kicks-in, it is there. Also, please remember not to use clumping litter with the little ones...they tend to eat it and it can be a disaster.

Normally, we like to introduce babies to the litter at the same time as we introduce them to moist canned kitten food. Your little ones might be a tad young yet ... but you can try. It is easiest to confine them to a small space with the litter and their food, I use an extra large dog crate while introducing them to these new things. It helps to contain the mess and they get the idea pretty quickly. Best of luck,

~gf~

Thanks for the replies, I think I'll wait a week and see how things are going, once I see more evidence in the box I'll put the litter in. I already have a shallow baking pan ready and I don't use clumping litter for my cats.

My orphans always started using the box around 3-1/2 to 4 weeks old but they didn't have a cat mom to clean up after them. Yours are getting close to using it.

when do ya start introducing them to wet food? my babies will be 4 weeks on june 1