Mine are 3 1/2 weeks (27 days!!), and they are just starting to figure out that whole litter box thing. It's SO CUTE to watch them go in there, scratch around, SCRUNCH up their faces and look SO focused, only to have them walk away with out doing anything!
But looking at your guys' eyes and ears, I, in my completely un-knowing opinion, would say they can't be that old. Yours' ears don't seem to be standing up yet, so they can't be that old. Do you have a better picture of their faces? And they way they are flopped around is still pretty baby-like. But I don't know!
This may seem odd, but you are bottling them, right? They have no kitty-momma? I know mine seemed to be further along their weaning and pottying when they were orphans (all 47 hours worth!). It's almost like, without mom there they knew they had to on their own (I did, but I guess I wasn't enough!), but now that mom is back they are being lazy again.
No matter how old they are, they are the cutest!
To show you what I am comparing them to:
13 day old baby face:
23 day old baby face:
(Not the same baby, by the way!)