Kanbaru's arc wasn't part of Monogatari Second Season, which contained the following arcs:
Nekomonogatari (Shiro) - Tsubasa
Kabukimonogatari - Mayoi
Otorimonogatari - Nadeko
Onimonogatari - Shinobu, and finally
Koimonogatari - Hitagi
Kanbaru's arc, Hanamonogatari, should technically have come before Nadeko's, but it is being aired seperately as a 5-episode series. As far as I know all 5 of them are being released simultaneously on August 16, after being delayed (original air date was supposed to be May 31 onwards).
So never fear, Kanbaru is getting her bit. Not sure why they shuffled it around like that though.
As for Koyomi's story - the prequel to everything - that's Kizumonogatari, and it was supposed to come out as a feature-length episode (a movie) in the same way as Nekomonogatari (Kuro). I have no idea what happened to that plan. I mean ... it was first announced in 2010, at one point scheduled to release in 2012 ... and then ... silence.
Maybe I should just take my copy of the LN and start translating it. Hopefully by the time the movie actually comes out, I'll have the first line translated