Other than personal preference, I do believe different cultures have different conventions. In Germany, salad was an accompaniment to the main course. It could substitute for the vegetable. I have noticed that with the americanization of Germany, many restaurants will now bring the salad first. Some pople eat it, some wait. In France, we always had the salad right after the main course; there it's usually a light dressing. In the US traditionally it comes before the main course unless it is the main course.