Yep, this is the age to introduce solids. If he has trouble with it you can mush it up with water (or KMR but I tend to feel that isn't necessary for a mother-raised kitten) but it sounds like he isn't having any trouble. His mother will likely let him nurse a bit for several months but will start reducing how often she allows it now that he's on solids. Now is also the time to introduce a shallow litterbox, because mama cat won't want to clean him up anymore! He should start grooming himself soon, too. I love watching baby kittens lick their paws---aww, it's so cute when little kitties act like big kitties .