You could start by simply upping the amount of baby food you give him at breakfast and dinner and start giving it too him for lunch. Around this age my son was eating cereal with 1/2 jar fruit &2oz bottle, lunch was 1/2 jar fruit and 1/2 jar veggie, dinner was 1/2 fruit and 1/2 veggie or dinner all stage 2. And 4 to 6oz bottles in between. Think of it as mini meals and as your son's appetite grows, you increase the amount of baby food up to two full jars at lunch and dinner. And you can feed him what ever you'd like in baby food as well. When 2 jars of baby food a meal don't seem to keep him full, you can start to go up to stage 3 1/4 to 1/2 jars at a time. Most of the fruits and veggies are only a tad bit thicker and your really chunky stuff is in the dinners. When he can eat those dinners pretty good, you can start mixing in some table food that is soft. Not going to happen till around 10 -11 months old though. And around 11 months you can start mixing his formula with whole milk to get that switched over. I started at 1/4 milk to 3/4 formula for every other bottle for 2 days, then to every day for 2-3 days. Then up to 1/2 and 1/2 for a few days every few days and then every day for a few more, etc till it is straight whole milk. I started 2 weeks before both of my kids 1st B-days cause they never had any allergies and transitioned to new foods without a problem.
Just follow your son's lead!! Good luck!
~S.