It depends on your country. For example It's 1 p.m. in Turkey and 6 p.m. in China 5 hours difference. Sunday : 星期日 , Monday : （星期一）

In my country, Saturday is the first day.

It indeed depends where you are. But in West-Europe we always learn Monday is the first day of the week because it is a schoolday and work day, first day after the weekend. But sometimes when we buy a calendar it does sometimes starts on Sunday.

This depends on where your are. In the West, Sunday is considered the first day of the week. You can see this on any calendar. This is despite the fact that Monday is the first work day. In China, Monday is considered the first day. Loosely translated, the Chinese word for Monday means "week's first day". Sorry if I've confused you even more.

The first day of the week varies all over the world. In most cultures, Sunday is regarded as the first day of the week although many observe Monday as the first day of the week. According to the Bible, the Sabbath or Saturday is the last day of the week which marks Sunday as the first day of the week for many Jewish and Christian faiths, while many countries regard Monday as the first day of the week. According to the international standard ISO 8601, Monday shall be the first day of the week ending with Sunday as the seventh day of the week. Although this is the international standard, countries such as the United States still have their calendars refer to Sunday as the start of the seven-day week. ( http://www.timeanddate.com/calendar/days/ )