Which of these quotes with a subordinating adverb is punctuated correctly?

A. Even so when I was invited to attend an important author event on the East Coast; a friend took me in hand.

B. Even so when I was invited to attend an important author event on the East Coast a friend took me in hand.

C. Even so, when I was invited to attend an important author event on the East Coast, a friend took me in hand.

D. Even so, when I was invited to attend an important author event on the East Coast. A friend took me in hand.”