How to set-up multiple cron task with wp_schedule_event so that they do not overlap?

Question

I'm using a cron to take data from Facebook and i have divided the job into three calls, to avoid making to many call all toghether, now how do i set up calls so that they don't overlap?

// Set the CRON for pages
wp_schedule_event(  current_time( 'timestamp' ), self::FB_CRON_FREQUENCY, self::FB_CRON_PAGES, array( Ai1ec_Facebook_Graph_Object_Collection::FB_PAGE ) );
// Set the CRON for groups
wp_schedule_event(  current_time( 'timestamp' ), self::FB_CRON_FREQUENCY, self::FB_CRON_GROUPS, array( Ai1ec_Facebook_Graph_Object_Collection::FB_GROUP ) );
// Set the CRON for users
wp_schedule_event(  current_time( 'timestamp' ), self::FB_CRON_FREQUENCY, self::FB_CRON_USERS, array( Ai1ec_Facebook_Graph_Object_Collection::FB_USER ) );

So i want all of the calls to run every two hours, but i want one to run at minute 15, one at minute 30 and one at minute 45 so that they do not overlap, how can i do that?

Answer 1

Ok that was pretty easy

// Set the CRON for pages
wp_schedule_event(  current_time( 'timestamp' ) + 450, self::FB_CRON_FREQUENCY, self::FB_CRON_PAGES, array( Ai1ec_Facebook_Graph_Object_Collection::FB_PAGE ) );
// Set the CRON for groups
wp_schedule_event(  current_time( 'timestamp' ) + 900, self::FB_CRON_FREQUENCY, self::FB_CRON_GROUPS, array( Ai1ec_Facebook_Graph_Object_Collection::FB_GROUP ) );
// Set the CRON for users
wp_schedule_event(  current_time( 'timestamp' ) + 1350, self::FB_CRON_FREQUENCY, self::FB_CRON_USERS, array( Ai1ec_Facebook_Graph_Object_Collection::FB_USER ) );