We had a similar problem with our ds, he's absolutely huge for his age, bigger than most babies a couple months older. He's not fat - ratios are good, just big and will definitely be a big person. So needless to say he's been a ravenous eater. What really helped us was putting a little bit of rice cereal in his bottles - like a teaspoon or less. That stretched things out a bit although there were still days when he would eat every three hours or so. We started him on solids at 4.5 months, and that has gone wonderfully, he's very enthusiastic about it. I had planned to wait until he was closer to 6 months, but then his doc said that when they hit 18 lbs they want and need real food. You might want to keep that in mind too! I wouldn't necessarily start him on rice cereal out of the bottle unless he weighs at least 18 lbs and you've run it by his doc.