4 week old kittens

I have 4 week old kittens from a stray that I have been taking care of. Mom is still nursing them. I have seen on websites that they will begin eating a mush of kitten food at 3 to 4 weeks. I have made it for them everyday for the past 4 days or so. They still have no interest in it. Also no interest in water. Is that OK? I am assuming the Mom knows best.

It's perfectly fine that they aren't ready yet. A few of my foster kittens started eating at 4 weeks but most started when they were 5-6 weeks old.
Also, they may not seem interested if you just set it down next to them. With my kitties, I put a little on my finger and put it right up to their nose/mouth and let them lick it. They realize really quickly that they like it and usually try it on their own.

I never give canned kitten food to my kittens till they are 5-6 weeks old - younger then that most do not show any interest and to avoid worry/frustration of them not eating, I just wait a few weeks. Very few kittens eat solid food that young unless you have to hand feed them.

And I have a water bowl with the kittens from birth - have had some lap water at 3 weeks, but most don't bother till around the time they are starting on solid foods.