We have no idea how long she was Lady, she may have ascended at the time of the Conqueror.
By the way there is a particular stone associated with the Conqueror, in Hastings, it is in the shape of a Stone Table. Where have we seen that before?
In 1066 The Conqueror overturning the British Monarchy was presaged by a daytime visible Halley’s Comet, often mistaken for a Star.
This may be the Stars And Stones, Mab executing her predecessor on the Stone Table at the same time Titania also became Queen when the first Mother Summer abdicated, all over lit by Halley’s Comet, causing Mab and Titania not to speak for 1,000 years. William becomes King, Mab becomes Queen.
That would suggest that the final triology volume Stars and Stones has Mab executed on the Stone Table probably by Harry, leading to Molly becoming Queen, probably during the height of the eta aquarid meteor shower, which are the remnants of Halley’s Comet apt, if Mab bites it. The Eta Aquarids are annual and peak during the first week in May. We are at December 2014 in the Dresdenverse, no really highly visible comets in the next 8 years of Harry’s timeline, and actually in 2022 Halley’s Comet is at aphelion, it’s furthest point from the sun, so my guess Mab dies in May 2022, having become Queen in 1066, having risen on the Star and fallen on the Stones. Prophecy? It would explain its use as a curse term the deaths of Queens of Faerie.
I know everyone thinks Syarrs and Stones is to do with the Black court and Drakul but the actual quote in Battle Ground Chapter 13 “This was never about raising an army, fool' Mavra hissed. 'It was about acquiring new blood for the stars and stones.” Add a comma after blood and the sentence changes completely, she is cursing, not explaining, not raising a Zombie army for the Fomor, but recruiting Black Court Wizards. Harry is good at Listening, but I doubt he can hear punctuation. This is exactly the type of sneaky trick Jim would pull, getting us all excited because Harry is literally an unreliable narrator.
I still have no idea WTF Starborn means. Unfortunately I suspect neither does Jim.