Some people observe a custom mentioned by the Shela Ha’kadosh (Rav Yeshaya Horowitz, 1558-1630) to immerse in a Mikveh in the afternoon of Ereb Pesah, with the intention of making oneself pure for the holiday. One should also have in mind at the time of the immersion that he wishes to bring upon himself the sanctity of the holiday with joy and enthusiasm. This practice is mentioned in other sources, as well, including the Kaf Ha’haim (Rav Yaakob Haim Sofer, Baghdad-Israel, 1870-1939) and the Hid”a (Rav Haim Yosef David Azulai, 1724-1806), in his work Moreh Be’esba (204).
There is a special Misva to wear fine garments on Pesah, even more so than on other holidays. The Torah tells that before Beneh Yisrael left Egypt, they asked their Egyptian neighbors for their fine clothing, and thus when they left Egypt on Pesah, they wore fancy clothing for the first time after over two centuries of poverty and subjugation. To commemorate this aspect of the Exodus, it is proper to wear especially nice clothing during the holiday of Pesah. Likewise, it is proper to ensure that one’s home is neat and to decorate it in honor of Pesah.
One should open the packages of Masot and the bottles of wine before the onset of the holiday, to ensure that he has enough for everyone who will be at the Seder. One should likewise check to make sure he has enough utensils for everyone, and that all the wine cups are the required size for the Misva.
The Kaf Ha’haim (454:41) writes that before Pesah one must make a point of paying for the Masot that will be used for the Misva at the Seder. According to some authorities, one does not fulfill the Misva if he eats Masa for which he had not yet paid. Acquisition through Meshicha (taking physical possession) is effective only Mi’de’rabbanan (by force of Rabbinic enactment), whereas acquisition through the transfer of money is effective on the level of Torah law. Thus, according to this view, when it comes to the Torah obligation of eating Masa on Pesah, one should ensure that he has acquired the Masa on the level of Torah law, and therefore one must pay for the Masa before the onset of the holiday. It is proper to do so in order to fulfill the Misva according to all opinions. Special care must be taken in this regard when purchasing Masa that was baked on Ereb Pesah, as some people have the custom of doing. People are normally rushed on Ereb Pesah, and it can often happen that the buyer will take the Masa on credit to save time. One should ensure to pay for the Masa before the holiday begins, rather than delay payment.
Summary: Some have the custom to immerse in a Mikveh on Ereb Pesah. There is a Misva to don especially fine clothing on Pesah, even more so than on other holidays. One should also make sure the home has a festive appearance. One must ensure before the onset of the Yom Tob to pay for the Masa that will be used at the Seder for the Misva, and not delay the payment until after Yom Tob.
