(Note, I've never hosted a formal dinner party and probably never will.) Hosting friends usually involves ordering pizza and letting people have free reign of the blender for boozy cocktails.
When my group of friends organizes events, it is typically done by group text. If the initial proposal is the 22nd and it does not work, and someone suggests the 23rd, everyone has their chance to veto it (to the group). If it is being hosted by someone, then host gets first dibbs on the date. (If it is at a public place like a restaurant, it is the date that works for the most people). Even a set in stone date (like a birthday) can be moved around (especially if the actual birthday falls during the week).
Bottom line is it is a know your audience type thing. But if I want to host something for 5 people, and the date does not work for 4/5, then I'm changing the date.