If you want my honest opinion....if it's starting anywhere between 4-7, then yes, I think you should serve SOMETHING, because that's the general dinner hour and likely people will be coming right after work.
Now, with that said, you don't need to get fancy or go all out, especially if you can't afford to. One thing I do that's quick, cheap and easy is grab a loaf of bread, some cans of tuna, make tuna salad sandwiches. Or if you've got eggs, boil them up, chop them and make egg salad sandwiches. Pre-make them and slice them diagonally and arrange them nicely on a platter. Like the previous poster said, put out some chips/dip, pretzels, veggies/dip, bottles of soda. If you've got nuts or candy, put some out in a dish. If you've got salad veggies, chop some up and make a tossed salad and put out some dressings.
I also do a pasta salad that is as quick as cooking the noodles and mixing. I use mayo, dill, garlic powder, onion powder, salt, pepper, and parmesan cheese. Sometimes I dice up tomato and toss it in. It's one of those dishes everyone always asks me to bring to potluck events.
Is the Pampered Chef consultant making a dish during the party? I know they usually do, so that's another item you'll have to serve.
Have fun and good luck!
Kimya