L.C.
I'm going to tell you what I did. I'm not saying it is right or wrong... I did what I thought was best and I'd do it again...
My #1 went 5 weeks on just formula. He was eating 5 or 6 8oz bottles a day... I fed him rice cereal with his last bottle at night. I needed sleep! He liked it thicker - personally I thought it was gross. I started with the cereal soupy... he spit it out. I made it thicker like oatmeal and he LOVED it!
With my daughter, she got cereal at a week. My husband was out of the country and I was TIRED. She liked it soupier, but that was probably because she was younger.
They slept. They were full.
They were happy.
I started veggies at about 8 weeks with my #1.
We started with orange veggies and went from there. We did fruit well after veggies... fruit is sweet - they all like fruit!
FYI: My sister - now grown and happy and healthy - was fed cereal upon her arrival home from the hospital.
YMMV
LBC