baby food problems 😑 HELP!

My little guy will be 6 months on Feb 9th and his pediatrician said he should be on first foods baby food by then and I literally can NOT get this baby to eat any of it! not even rice cereal or oatmeal! He takes rice cereal in his bottle but that's it! If I try giving him any kind of baby food (even home made baby food) he makes an awful face and ends up making himself gag then throws a fit if I keep trying ... I don't know what to do ! can anyone shed some light here an give me tips etc?