Actually, Kizumonogatari comes first. I have no idea why they animated Bakemonogatari before it.
The novel series was not published in chronological order, but the narration of each novel occurs chronologically. Kizu is narrated by Koyomi
after the events of Bake, just as Tsubasa Family occurs between Kuzi and Bake but is narrated by Koyomi after the events of Nise. The anachronic structure was most likely publisher imposed for Bake and Kizu, but since then, the author has used it for the purposes of character development.