Read the following passage and answer the questions

Tet holiday is celebrated on the first day of the Lunar New Year in Viet Nam. Some weeks before the New Year, the Vietnamese clean their houses and paint the walls. New clothes are bought for the occasion. One or two days before the festival, people make Banh chung, which is the traditional cake, and kinds of jam. On the New Year’s Eve, the whole family get together for the reunion dinner. Every member of the family should be present during the dinner in which many different kinds of dishes are served. On New Year morning, the young members of the family pay their respects to the elders. And the children receive lucky money wrapped in red tiny envelopes. Then people go to visit the neighbors, friends and relatives.

1.When is Tet holiday celebrated in Viet Nam?