The idea that the birth of a king should ideally take place when the sun was conjunct with Regulus seems to have been a common conception throughout the Middle East.
Gilbert even goes on to associate this celestial conjunction - which he calls 'Regulus day' - with the Aker-lions:
The [Great Pyramid] itself was a 'horizon' over which the sun would pass in such a spectacular manner on Regulus day.
The name Akhet [= 'horizon'] is also clearly linked with another important symbol in the religion of the ancient Egyptians: the double lion or aker. This symbol shows two lions, one facing east and the other west.
As if this wasn't enough, the 'Regulus day' conjunction of 2003 (August 22-23) will be extra special because the sun-Regulus alignment will be joined by not one but two more planets, Jupiter and Venus. In other words, we'll have a ridiculous Sun-Regulus-Jupiter-Venus-Earth alignment on the eastern horizon while 'from the sky will come a great king of terror' called Mars on the western horizon! (Click on the image below to see an animated gif image.)
The significance of the Mars positioning is also amplified by the fact that it will be in the constellation Aquarius. In the 'Time River scheme', Aquarius happens to correspond to the region of Iraq, i.e. the 'land of Mars' and the Osirian Underworld!