My son is 11 months. My original plan had been to breastfeed until 12 months, and then gradually wean. Now, I'm not planning on rushing it - we'll just see how things go over the next few months.
That said, neither of us does well physically when we ramp up the amount of solids too fast. We've had periods of time where he has trouble pooping and his stomach is really bothering him, and I have plugged ducts, when we've tried increasing solids too fast. I've only recently started giving him lunch (he had been getting just breakfast and dinner), but I've tried to keep the overall volume of food roughly the same so we both have a bit of time to get used to it. He is also not a fan of finger foods yet - I've given him some various finger foods, and all he does is play with them but doesn't put them in his mouth. If I put them in his mouth usually he just spits them out. He does fine when fed purees and chunky purees, though, usually.
How do I know how much food is enough at this stage? I don't want to over-feed solids, but I guess we should be increasing solids at this point to the level that his system can handle it (which as I said has to be a gradual process). I just don't have a good sense of what volume he should be getting, while still leaving room for nursing. How much he nurses varies greatly depending on if he's teething, if he seems to be in a growth spurt, etc. When not teething, I think he generally nurses around 8-10 times per 24hr period (including 2-3 times per night).