7 pm seems like dinner time to me. If you invited me for a party then, I'd expect that to be my dinner. Appetizer-type foods only would be fine, but I'd make sure you had loads, because your guests will be hungry and filling up on them.

You will really have to be careful about how you word the invitation. "Hors d'oeuvres" implies before dinner, not after.

If you want to make sure people don't expect to make a meal of it, call it "desserts" or "cocktail party." I'd do a cocktail party at, say, 5:30 - 8:00, and desserts at 8:00.

I'm not saying you have to feed guests a meal every time you entertain. But if you don't, then don't make it at a meal time. It's not considerate of your guests, and it will backfire on you if you only prepare a little bit and the first guests eat all of it before the others come.

If you do 8-10:00 people will expect heavy appetizers and dessert and drinks. Still-you will need heavy food, not just cheese and crackers.
We are trying to figure out a not disimilar situation.
A celebration or "meet and greet" for S and new wife but not a main meal. We are thinking 1-4 and will have many finger foods and a dessert bar. Drinks will be sparking ciders and Cava, coffee, tea, water. Am thinking we will skip pop altogether.
I will look forward to your posts. How many do you expect?

I'd start later than 1 pm if you don't want people to be expecting lunch. 3-6 perhaps.