???? ???? ???
The reason for this theory is because the passuk states ????? ??-????? ????, ???? ???. Since the entire month is referred to as the Month of the Geula, Therefore one could easily come to the conclusion that the mitzva begins at the beginning of the month, therefore it says ????? ??, meaning only at the time when one has the matzah and marror in front of them.
R’ Moshe Sternbuch in his sefer Ta’am Vo’aas (on the Hagadda) says that there is a fundamental lesson to be learned from this. There is insufficient time to state all of the accolades and miracles of HaKadosh Baruch Hu. Nevertheless, one must serve Hashem in the way we are instructed to. The Philosophers get it wrong. They will praise Hashem and learn about his wondrous ways, but they lack the main focus, which is the fulfillment of the mitzvos. Therefore it becomes a mitzva seder night to tell the story of Yitzias Mitzraim, to teach us that the Ikar is keeping mitzvos, for that is what connects us to Hashem.
(R’ Sternbuch concludes by stating that the Gra went as far as to not say Avadim Hayinu on Shabbos HaGadol, since he saw from the drasha above that it was not its proper time).