Starting baby on cereal early

Anyone give put cereal in their babies bottle earlier than recommend? My son is really eating back to back . I can deal with it during the day but at night I’m not getting no sleep to the point that I’m getting headaches now , and what makes it worse is that at night it’s CONSTANTLY because he will fall back to sleep while drinking his bottle but will only drink up to about 2oz instead of his usual 6oz so then again he’s waking up for another bottle about 1-2 hours later . How old was your baby when you put it in there ? I really just wanna do it in the night time bottle