I did it once because my mom kept saying I needed to so she would sleep through the night. Around 4-5 months. She started chocking and I never did it again
I never did cereal in a bottle. I tried oatmeal at 6 months and she didn't tolerate it, so I tried again at 8 months and she was fine. If I had it to do all over again I would skip the grains and just do fruit and veg.