The complicated domestic calendar has been blamed for falling attendances at Twenty20 matches.
The group, which convened on Tuesday in the first of two meetings, said reducing the number of days would "enable a coherent and balanced domestic schedule to be delivered".
An ECB statement said: "The group will recommend that quarter-finals for the Clydesdale Bank 40 competition be delivered from 2012 and that the competition should be played in four pools of five teams.
"The group further noted that following the ICC World Cup in 2011 the format of international ODI cricket will be reviewed and recommended that the format of the Clydesdale Bank 40 competition should mirror the international format."
