I had the same question a while ago about my son, now also 7 months. I went on the American Academy of Pediatrics and they reccommended the following for infants over 6 months.
2-4 Tbsp of cereal 2 times a day
2 tbsp veggies 2 times a day
2 tbsp fruit 2 times a day
My has to following eating schedule:
wake:
Breastfeed & Breakfast
(couple tbsp cereal mixed w/2 tbsp fruit)
Lunch:
Breastfeed & Lunch
(3 tbsp veggies)
PM snack - nurse
Dinner:
Breastfeed & Dinner
(2 tbsp veggies, 2 tbsp fruit)
I seem to be feeding him a lot more than most of you...maybe i'm doing too much? He alsways finishes what I give him and would eat more if I offered it. But he really isn't a heavy baby, and I always nurse before he eats to make sure he's filling up on breatmilk first as that is the more nutritious than food.
Good luck! :)