This is something that may confuse you and I just want to explain to clarify. I do look at fixed stars a lot on Solaris Astrology and I think they are just as vital and important as the planets, indeed the constellations we know get their reputations and meanings from the stars that are placed within and make them up.
As I mentioned fixed stars are not fixed, they do move about 1 degree in relation to the earth every 70 years or so. If you do your sums, then a fixed star will move the 30 degrees of a sign in around 2100 years. That's why the main star in Leo Regulus is now at 1 degree Virgo and Acubens in Cancer that I just wrote about earlier today now sits in the sign of Leo.
This ties quite nicely into the first known appearance of the zodiac as we now know it. The zodiac constellations representing the specific areas of the sky we look at as Astrologers were fixed in position in relation to the movements of the Sun, however the actual constellations on which these were initially based have shifted just over one sign since these positions were designated. Back around 500BC the Babylonians had 18 irregular zodiac signs and these seem to have been paired down to 12 equal sized signs of 30 degrees in or around 50BC when the Dendera zodiac was created. The first known actual depiction of 12 signs in use today can be seen in a bas-relief taken from an Egyptian temple in Dendera. If you are interested, it can be seen on show in the Louvre Museum in Paris.