This would put Khoronus before Blackmoor era. I though he was an early Blackmoorian...

EDIT: I double checked what I remembered and in Dave Arneson's Blackmoor Campaign Setting book (page 159) I found out that Khoronus was a mortal man "just" two hundred years before the start of the campaign, that is 1030 (after the foundation of Thonia), so Khoronus lived around 830 (approximately the time of the Mage Wars). Is it approx 3170 BC, according to the Thiatian Calendar?

When would you place Temrin?
http://blackmoormystara.blogspot.com/20 ... -part.html :)

Where would this fit in the proposed chronology? And then when would you put his death? at the rise of the civilisation times?

I have no hard facts to judge either Marco's nor your chronology. It just feels that Marco's is too grand and extended, wile yours is too compressed: the whole history since the time of Ser Aigu would be just a few thousand years and longer living sentient beings like Elves would have seen dramatic changes in just a few generations.
Maybe something in the middle?