I have been playing with astronomy programs (cybersky) and thinking about the origins of the zodiac. It would make sense if the original zodiac was referenced to a prominent star on the ecliptic (the path of the sun across the sky). The two most popular candidates would be Spica in Virgo and Regulus in Leo. These two prominent stars have always been associated with their respective constellations and are now about 54 degrees apart and since the zodiac is divided into 12 units of 30 degrees and leo and virgo are adjacent constellations, Spica must have always been in the eastern part of Virgo and Regulus in the western part of Leo. There is a Hindu zodiac which uses Spica for a reference point but I will focus on Regulus because it is timely now.
Regulus would be closest to the actual path of the sun, and one of the ancient names of it is Rex, or the law giver, interpreted by some as setting the starting place of the zodiac. The Sphinx is thought by some to be associated with Leo, and Regulus would have been at the zero point of ecliptic longitude in 8884 BC at the end of the age of Leo (the Sphinx faces east, greeting Regulus at sunrise and may date back to this time). The beginning of the age of Leo would have been about 2160 years earlier.
If we accept that Regulus was used as the western boundary of Leo, then the eastern boundary of Aquarius would be 150 dgrees of ecliptic longitude west of Regulus. The beginning of the Age of Aquarius would then be that time when Regulus would be at 150 degrees of ecliptic longitude, which just happens to be right now. The traditional interpretation of the ages of the zodiac begins when the vernal equinox enters the constellation, so we may have to wait until spring for the real celebration to begin. If you would rather conclude that Spica is the original reference point , then you will have to wait until 2262.