In french culture, Chrétien de Troyes (1130-1190) is respected and his work still studied, as the first french novelist, and the first to write about arthurian mythos and to "invent" the Graal.
But King Arthur Pendragon and his GPC is massively based on Thomas Malory's work, and Chrétien's is a tertiary source at best. I think it's a missed opportunity. To be more faithful to the french sources, more ancient than Malory by a few centuries, I tried to insert more Chrétien in the GPC, to make it more to my taste.
First, let's begin with my favorite novel, Yvain ou le chevalier au Lion. It's a great arthurian story anyway, and I encourage everyone to read it. There is some differences of course. In the french novel, Yvain et Gauvain are first cousins by their fathers. In the english one, they are related by the mothers. In the french novel, Yvain, already the son of King Urien, is not the son of Morgan le Fay! And yet, she is portrayed in a positive light as a healer. Anyway...
In 522, The GPC said that Yvain [the french way, I'm a rebel] is dubbed and goes immediatly to the Triple Quest (like in Malory).
In 523, after a year of questing, he is at the court of the King Arthur, to tell his adventures.
In 524, he is appointed to the Round Table, with his nickname "The Knight with the Lion".
Considering that the novel begins at the Royal Court, and he gained his nickname during the adventures of the novel, case closed: The adventures of the novel are setted in 523. Except... there is still some issues. His adventures are segmented into half. In the first half, he revenged his cousin Calogrenant, marry the duchess Laudine, and he is happy and then go to tournaments. In the second half, one year after, he became crazy after betraying his love before going for many mores adventures, with a finish in duel against Gawaine.
The GPC is still working. The first adventures and his wedding are in 523, and the rest in 524. The GM can add to the GPC the events of the novel during this two years. Or, he can be even more ambitious, and adapt the novel for his players...