Feed him milk. If you can snap a few pictures showing your open palm alongside the kitten, I might guess its age.
Or if you think that he is big enough, then cut very small pieces of meat (1 to 1.5 centimeter long) (feeding liver will lead to improvement in cat hair after a few months, they will become silkier and cat will become stronger). Give it a few pieces, if he eats it then its good.
Also to train a cat, put some sand (or refined dirt, no pebbles or stones) in a shoebox. Keep putting the kitten in or near the shoebox after a few hours. He will automatically understand that he has to go potty there.
Cleaning the shoebox will be a hurdle though lol. Bhallu asks me to either open the back door (keeps meowing) or goes from the front opening of the house to empty himself.