I wrote:

>I have my doubts about the explanation that the salad course comes first --
I seem to
>recall reading somewhere that in the 19th century, salads did not come
first; so, the salad-
>first custom may not be old enough [to explain the "salad days" reference in

In support of this rcollection, I'll quote from Miss Manners at:

"Most of these courses have been eliminated, and the standard formal meal is
soup, fish or meat (but occasionally still both, as separate courses in that
order), salad, dessert and//or fruit.
 Often, nowadays, people will start with the salad because they have picked
up the habit from restaurants, where formal service has been altered for the
practical consideration of staving off hunger while the main course is cooked."

So, if you can believe Miss Manners, salad-first is not a tradition unchanged
since the middle ages, but a recent custom driven by the needs of the
restaurant industry.