Cerelac at 4 months

Hi mummies, im in a dilemma here. Both mothers said to me my LO can have a bit of cerealac once LO reaches 4months and I’ve forgotten to ask the paediatrician whether my LO can take cerealac. But after reading articles that babies should be introduced to solids when they are at 6 months im like worried if i made a wrong decision. I want to listen to the doctors but both mothers are telling me its fine, help me. I’ve not yet fed her fyi