2016 is a leap years. On the Roman solar calendar, one day is added every four years. A year is the earth's orbit around the sun. Leap day is February 29. The Julian calendar (365.25) was replaced by the Gregorian calendar (365.2425) which omits three leap days every 400 years. This reduces the error from 11 minutes (day every 128 years) to ~26 seconds (day every ~3330 years).

God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years (Genesis 1:14).

The Muslim use a lunar calendar. There are twelve months with about 354 days in a year. Because there are no leap months, annual holidays such as Ramadan occur about eleven days earlier each year. After ~33 years, the calendar is one year ahead of the Roman calendar.

The Jewish lunisolar calendar differs from the Roman calendar. Days begin at sunset. Months begin with the first observation of the new crescent moon. The Jewish culture has two major new years. The civil new year begins in the late summer or early fall on the 1st of Tishri. Genesis is beginning or Aleph b'Tishri. On Rosh Hashanah or Trumpets, add one to years from creation. See Jewish New Year. The religious new year begins in the spring on the 1st of Nisan.

In the beginning (Aleph b'Tishri), God created the heavens and earth (Genesis 1:1).

The Lord spake unto Moses and Aaron in the land of Egypt saying, This month (Nisan) shall be unto you the beginning of months: it shall be the first month of the year to you (Exodus 12:1-2).

The Jewish calendar has a leap year. A regular lunisolar calendar has twelve months for a total of about 354 days. A thirty days month of Adar I (Adar Aleph) is added after Shevet and before Adar, giving thirteen months. This keeps the calendar synchronize with both lunar months and solar years. A leap year is added every two or three years.

By 358 AD, Hillel II, leader of the Jewish Sanhedrin, implemented a perpetual calendar with a nineteen-year cycle. Seven years are leap years. There are postponement rules so a high Sabbath is not next to a regular Sabbath. In history, we can calculate when holy days occur based on phases of the moon.

Let no man judge you in meat, or in drink, or in respect of an holy day, or of the new moon, or of the sabbath days: Which are a shadow of things to come; but the body is of Christ (Colossians 2:16-17).

Prophecy is about time and events. God wrote His redemption plan in the constellations and named the stars. The story begins with the virgin birth and judgment, the sacrifice of the bull, sheep and goat, Christian and messianic Jews are believers and He returns to collect His sheep and rule as the Lion of Judah. People use the sun, moon and earth to track time but also track His plan. World events are written into Jewish holy days so Columbus, World Wars, Iraq Wars, Tribulation and End Wars occur on these days. See Jewish Calendar, America Articles.

Come, and let us [Israel] return unto the Lord: for he has torn, and he will heal us; he has smitten, and he will bind us up. After two days will he revive us [1948]: in the third day [Atonement] he will raise us up, and we shall live in his sight (Hosea 6:1-2).

References: 21st Century Revelation: World Wars, Iraq Wars & End War Chapter 9 - In the Beginning, God, Chapter 10 - Seven Days of God, Chapter 18 - Spring Forward, Fall Back, Spring Feasts,  Pentecost, Fall Feasts, Calendar, Jewish Calendar, Bible Chronology, Hebrew Calendar, Constellations, Revelation Outline, Covenant, Tribulation, Revelation, 21st Century View, Daniel, America, Timeline of the Tribulation