My son started feeding himself guacamole, applesauce and rice at four months and is now a happily self feeding nine month old. My doc gave me the go ahead because he was sufficienctly developed to swallow at that age. he still nurses daily but eats just about everything we do now. If they're ready to try foods, just mash it up and let them try some. Every baby is different and every baby has their own schedule. if they're grabbing for your food and getting it into their mouth and repeating the cycle, sitting on their own, they're ready!
have fun trying new foods! we did avocado, applesauce, green beans, peas, bananas first.