When is the earliest time one can start the Seder if one has elderly people at his Seder? Can one follow the Gra? Whats the Gra shita in the New York area?
One should not start the Seder before nightfall (tzais ha-kochavim), because all the mitzvos of the night must be fulfilled after nightfall, including the Four Cups.
Kiddush must therefore be made only after nightfall.
However, one can rely on the opinion of the Vilna Gaon to start the Seder “early”, in particular for the mitzvah of the Four Cups, which is Rabbinic.
I do not know the time of the Gra’s opinion in New York, but this can probably be found in the calendars.
Best wishes and sorry for the delay in replying.