There is a custom that should be observed on the night of Shabbat and Yom Tob to first look at the Shabbat or Yom Tob candles before beginning Kiddush. Many different Segulot ("charms") are associated with this practice. The Gemara, for example, comments that viewing the candles is beneficial for the eyes and brings healing.
Furthermore, the two Shabbat candles represent the notion of raising children to be Torah scholars. The Gemara comments, "One who is accustomed to lighting the [Shabbat] candles will have children who are Torah scholars." The two candles signify the husband and wife. A man has 248 limbs in his body, and a woman, because of the female reproductive system, has 252. Together, a husband and wife combine for a total of 500 limbs. The numerical value of the word "Ner" (candle) is 250, and thus the two candles, which combine for a total of 500, represent the union between the husband and wife which produces children. Indeed, the phrase "Peru U’rbu" ("Be fruitful and multiply") has the numerical value of 500. For this reason, the Gemara in the aforementioned passage speaks of "Ha’ragil Be’ner" ("One who is accustomed to [lighting] candles." The word "Ha’ragil" has the numerical value of 248, and the word "Be’ner" has the value of 252, alluding to the union between husband and wife, who together beget children and, through the merit of the candles, raise them to become Torah scholars.
This custom is a very easy one to observe, and yields many important benefits. I once saw a certain Torah Sage who was prepared to recite Kiddush on Friday night but started motioning and gesturing to somebody at the table. It turned out that this person was obstructing the Rabbi’s view of the Shabbat candles, and he did not want to begin Kiddush until he could see the candles. This is one reason why the women should ensure to light the Shabbat candles near the table where the Shabbat meal is eaten. If the woman lights in the kitchen and the Shabbat meal is eaten in the dining room, the husband will be unable to view the candles before Kiddush. The wife should thus ensure to light near the table where the Shabbat meal takes place, so that this custom can be properly observed and its benefits can be accessed.
Summary: It is customary to look at the Shabbat candles before reciting Kiddush, and one should make a point of observing this custom.