My kids were done with baby food long before 1 year (because they didn't want M. feeding them, they wanted to feed themselves), so my experience is different.
I pulled the high chair up to the table and sat down next to them. I would have a plate full of my food and place a few pieces on their tray. When it was gone, I added to it. When they started trying to climb out or started throwing food, I just took that to mean they were done and helped them down.
I started to learn their behavior when they were hungry and responded with more food. Often times it would be a hour or two after their previous meal. Sometimes I would just notice it had been a couple of hours and offer them some food.
I really feel your best bet is to make it a lot less structured and just go with the flow. Follow his cues. He's getting to the age where they will eat and eat and eat (what may seem like an adult size meal) one day and then survive on 3 or 4 bites the next. It often seems like there's no rhyme or reason to their patterns. And there might not be. That's just what toddlers do.
I would definitely stop using rice cereal. It has little to no nutritional value. It's a starter food because almost no one is allergic. You're better off serving oatmeal or cheerios. Something that offers him more nutrition.
Relax and follow his cues. You'll be fine!