When Erev Pesah falls on Shabbat, one should preferably recite "Minha Gedola," meaning, he should recite Minha during the early afternoon hours. Halacha forbids eating meals late in the afternoon on Erev Pesah, in order that one will sit down to the Seder with an appetite. As such, when Erev Pesah falls on Shabbat, one must eat Se'uda Shelishit (the third meal) early in the afternoon, and thus Minha should also be recited early.
On the afternoon of Erev Pesah, the prohibition against eating Hames already applies, and it is likewise forbidden to eat Masa. Therefore, on Shabbat Erev Pesah, one may, according to the strict Halacha, eat other foods (besides bread) for Se'uda Shelishit, such as fruit, salads, meat and rice (according to the Sephardic custom allowing eating rice on Pesah). Some, however, boil or fry Masa before Shabbat and eat it for Se'uda Shelishit. (One recites Ha'mosi over boiled or fried Masa.) Another custom is to partake of Egg Masa for Se'uda Shelishit on Shabbat Erev Pesah. As mentioned, however, strictly speaking one may partake of other foods, even though on ordinary Shabbatot one's Se'uda Shelishit should include bread.
On the afternoon of Shabbat Erev Pesah one should recite the text of "Seder Korban Pesah" which is printed in many Siddurim and Haggadot. This text consists of passages from the Humash and Mishna that outline the procedure for the Korban Pesah – the paschal offering that was brought on Erev Pesah during the times of the Bet Ha'mikdash. Nowadays, when we cannot actually perform this Misva, we commemorate the Korban Pesah by reciting this text, so that through our study we will be considered as though we actually brought the sacrifice. One should recite this text on Shabbat Erev Pesah after Minha, either before or after Se'uda Shelishit. (The text is available for download from www.dailyhalacha.com, by clicking ‘Download Special Tefilot’ on the left of the home page.)
As mentioned, one should not eat substantial amounts of food late in the afternoon, so that he will have an appetite for the Seder.
When Shabbat ends, women should recite, "Baruch Ha'mavdil Ben Kodesh Le'kodesh" and then light the Yom Tov candles. Halacha forbids kindling a new flame on Yom Tov, and therefore one must light the Yom Tov candles from a preexisting flame, such as a pilot light or a candle that had been lit before Shabbat. When lighting the candles a woman recites the Beracha, "Asher Kideshanu Be'misvotav Ve'sivanu Le'hadlik Ner Shel Yom Tov." Our practice is not to recite "She'he'heyanu" at the time of Yom Tov candle lighting.
After a woman lights the Yom Tov candles, she may begin making the preparations for the Seder.