A few months ago, I heard a couple people talk about this topic at the Office Optional conference.
http://officeoptional.co/program/
As you will see in the link, the people I'm referring to are
a) Cass Phillipps @webwallflower
b) Christina Lucey @christinaluce
It would be worth reaching out to them to get specific advice as they've dealt with the specific issue of working across timezones.
You can even tell them that you found out about them via the Office Optional program.
Hope that helps.
