When should bans kick in?

Seven leading Russian women athletes have been banned for two years for manipulating doping samples. The timing of the suspensions, however, runs counter to the demands of the sport's world governing body, the IAAF, who insist the suspensions should start from when the athletes were provisionally suspended in July 2008, while the Russian Athletics Federation say the bans will be backdated to the times of the tests in April-May 2007. When do you think the bans should start from? Have your say now!