feeding solids??

Erin
Hey guys another question for you. At what age did you start introducing solids? My baby boy is 15 and a half weeks and I know that's super early to introduce anything but formula or breast milk BUT my little man was born at 7 pounds 7 and a half ounces and 20 inches long and is now 27 inches long and 16 pounds. He is holding his head well and sitting assisted. I strictly bottle feed because I was never able to produce milk but at this point He is basically refusing the bottle and it's been several weeks. He will eat a few ounces here and there but rarely a solid meal of 3 or 4 ounces, he always seems hungry and his longest stretch of sleep is only about 3 hrs before he wakes up ravenous. He has a dairy sensitivity so he is on sensitive formula per doctors orders and a probiotic and it's helped, but still hasn't solved the issue. Any suggestions? Would it really be harmful to introduce some rice cereal or single fruits and veggies?