My son was a big eater (still is, he's now one and eats the same amount at breakfast & dinner as I do, his lunches are usually a little smaller). We started him on rice at 3 months. By four months he was on stage one foods. We started with yellow veggies, then green veggies, then fruits (fruits are really sweet & kids usually love them, they say to intro them last so they don't reject the "plain" veggies). By 5 months he had tried all the stage ones & was on to stage twos. By six months he was on stage 3 and eating finger foods. Most doctors today will tell you this is too fast, but every kid is different, this is what worked best with our son.
I think 1 tbsp of rice to 4 of formula sounds really runny. I never actually measured anything myself. I used to dump some rice in a small bowl & add some water until it looked to be a good consistency. I never made mine really runny, it made too much of a mess. I also think stage 1 and 2 foods are too runny. I used to make my own with much less water & he could swallow it just fine.
When we started him on food I gave him the rice at dinner time. I gave him as much as he was willing to eat. At first that was less than a tbsp. Within 2 weeks he was up to about 5 tbsp (i'm told this is an unusually large amount for a baby at one sitting, but again he was fine). I always stopped when he turned his head away. We later added a second solid rice meal at breakfast. Again as much as he would eat. By 4 1/2 months we were up to 3 meals a day, varying rice, fruits & veggies (a different thing at each meal). And at each sitting we let him eat as much as he wanted. This would change every day. Sometimes it was only 1/2 a jar, sometimes a whole jar, sometimes 1 1/2 jars (this was usually during a growth spurt). When he regularly ate more than a jar we went up to the stage 2 foods. When he was regularly eating more than one jar of that at a sitting we went up to stage 3.
I always fed him close to my meal times (either just before or after I ate) I figured this would make the transition to regular foods & meals with the family easier. It seems to have worked.
When you get to the stage 3 foods, make sure you read the ingredients; especially if you get their early. I was shocked & found out most of my friends had no idea what was in some of them. Many of them have added sugar. All the "desserts" do, but so do some of the others. Also a lot of the dinners have eggs in them. Babies are not supposed to get (I think I have this right) yolks til 9months & whites until 1 year. Some of the dinners had egg whites, egg yolks, or even whole eggs in them. So make sure you check. This is not a problem with stage 1 & 2 foods.
Good luck