The mitzvah of reciting Kiddush is scriptural in origin and alluded to in the Aseret Ha-Dvarim. Our Tora says, "זכור את יום השבת לקדשו" meaning "remember Shabbat in order to sanctify it," Chazal has said that one fulfills it by saying the text of kiddush on Friday night. This is highlighted by Rambam in his Halakhot on Shabbat chapter 29.Further, Shulchan Arukh writes that when one returns home from the synagogue on Friday night, one should immediately recite Kiddush. Yisrael Meir Kagan mentions in his Mishnah Berura that if one is not hungry when one returns, one may wait to recite Kiddush since one already sanctifies the Shabbat during Arvit shel Shabbat.
He further adds that for the sake of one’s wife, ones children or out of town guests, one should not delay Kiddush and the ensuing meal. (This holds especially true in the summer months when Shabbat begins and ends later.)
Accordingly, if one sees that one’s wife or guests may be hungry, tired or the like, one may forego all the introductory portions of Kiddush, such as Shalom Alechem, Bar Yohai or Azamer Bishvahin and recite them after Kiddush.
Standing or Sitting (Minhag
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As for the actual drinking of the Kiddush, however, one should sit since Gittin 70a explains that drinking while standing damages the body.
Despite this the Hassidic minhag is to stand while reciting Kiddiush then to sit drinking at between 3 and 4.4 ounces of wine or juice.
Halakhic opinions:
Shulchan Aruch 271:10 rules that one should stand for Vayichulu, implying that one should sit for the rest of kiddush. However, (quoted by Aruch HaShulchan 271:21) Ashkenazim should stand for kiddush out of respect for the Shabbat queen (similar to the reason Ashkenazim stand for Havdalah, see Mishna Brurah 296:27).
Lastly, Rama comments on S.A in 271:10 and writes that Ashkenazim is permitted to stand for the entire kiddush, but that it's preferable to sit. R. Moshe Feinstein z"l in his Sh"t Igrot Moshe 5:16 states that the Rama only wrote that it was permissible to stand for kiddush, and that if one doesn't have a Minhag from his father he should follow the Shulchan Aruch.
Shabbat Shalom
Friday Night Kiddush