When the yanks start there day,but also used to find when they close could be good(better also as our morning,and same for the poms,again for our time,when they wake up,which used to be right about when i was trying to make dinner at 100 MPH so as not to miss anything,although the above was for usd/chf,usd/jpy,eur/jpy and eur/usd.
http://aboutforex.com/clocks.html
Cheers
Miner