Does Christianity need to read the Gregorian calendar?

Do foreigners have to look at the Gregorian calendar when they get married?

Foreigners don't have a yellow calendar. They use the solar calendar to calculate the year, but they should also choose a good day. When they hold a ceremony, they will go to the church and ask the priest to marry them.

Foreigners don't pay attention to the Gregorian calendar. They think that time is enough, the weather is good and everything is fine.