After you board, I believe they come around first with drinks and a snack (tiny bag of little cracker things) and then they will serve dinner. So, dinner is probably around 8:30 pm. Then about an hour or so before you land, they will serve breakfast.
I have flown economy with Swiss numerous times in the last couple of years. I’m not sure if the food is different in business class, but my dinners have been the option of a chicken or pasta meal. Both come with a roll, a small salad and small dessert. Breakfast is yogurt and a croissant I think.
If you are taking the afternoon Swiss flight to return to Chicago, I think it’s lunch and an ice cream snack you get. In March, lunch was a pizza pocket type thing. They also had some food items you could purchase. We got our favorite paprika potato chips.
Now that i'm remembering, i think for the "better" seats they came around with a tablet and were asking people want they wanted. So, you might have some better food options than what i had. But the time was the same--about 8:30 for dinner.