How much food at 9 months?
At 11 months that wouldn't be a problem for me. It still depends on how dense/dry the meal is though. I can do 4 or 5 eggs in an egg salad but only two hard boiled eggs plain.
I've seen some people suggest doing a couple of days of protein shakes to "shrink" the tummy but I'm not sure that is really what would be happening. Mostly, people just try not to overfill themselves to prevent stretching out the stomach.
Now that I have more capacity I watch my protein count to make sure I don't go higher than I want instead of early on making sure I didn't end up too low. It's much easier since post-op I'm just not as interested in eating like I was pre-op. Maybe interested in a different way post-op would be a better way to put that.