I am currently nursing my 23 month old, and also nursed my older son till he was 29 months.
What I always did was always nurse immediately before feeding them solids. Right now, he doesn't really NEED any nutrition from solids, it is mostly just to learn how to eat. It isn't until closer to his first birthday that he should be getting any significant amount of his nutrition from solids. That being said, I know some babies just really LOVE to eat. My little one now is like that, and he moved away from nursing a little quicker than I liked because he enjoyed food so much (I mean, yes, I am still nursing, but for him at this point it is only linked to sleep time so that is why he continues, but he was nursing less and less often faster than my first). I wouldn't discourage him too much if he seems hungry, but just make sure he gets the breastmilk first. This should fill up his tummy enough that he won't get too over involved in the solids. Also, don't rush the meal times with the solids, feed him a little more slowly, that way the message has time to get from the tummy to the brain that he is full . Babies do become a lot more efficient at this time with nursing, so it is normal that he is nursing for such a short time.