Halacha requires that one set the Seder table before the onset of Pesach, so that he can begin the Seder immediately upon returning home from the synagogue. It should be noted, however, that the Seder should not begin before Tzet Ha'kochavim (nightfall), which in the New York City area occurs approximately 40 minutes after sundown.
In communities outside Israel, where a second day of Yom Tov is observed, one may not set the table for the second Seder during the first day of Pesach; one must wait until at least 20 minutes after sundown. Since it is forbidden to prepare from one day of Yom Tov to the next, one may not begin preparations for the second Seder until the second day of Yom Tov begins. It is similarly forbidden to cook or warm up food for the second Seder before twenty minutes after sundown.
Halacha requires that one set the Seder table with his finest chinaware and cutlery, as on this night we celebrate our freedom. Ironically, people generally tend to use their lowest-quality utensils on Pesach. But one should use specifically his finest utensils, in order to properly celebrate and personally experience our nation's freedom, as the Haggada requires, that on the night of Pesach one see himself as he personally left Egypt on this night.
Summary: One should set the table for the first Seder before Yom Tov; for the second Seder, however, one may not begin any preparations until twenty minutes after sundown. One must set the table with his finest dishes and cutlery.
