I went when I was about four-five months with my second one. I remember getting extremely hungry. I would feel like throwing up and passing out at the same time. Just remember, that you can't go on a normal vacation eating schedule. You have to eat like you do at home. A churro or some fries probably won't cover it when you start to feel that way. Try to take notice of where you can find protein and a place to sit down. Or bring something along to snack on that is filling for you.
Other than that, I didn't really notice much else. I probably got pretty tired, but I was still pretty mobile at that point and wasn't really showing that much. I don't remember it putting a damper on the day other than the eating!
Have fun!