Is there a way to schedule a sync between DTPO my desktop and DTTG on my iPad?
Sync has to be initiated from the iPad, and DTTG does not have a feature to schedule a sync. Maybe someday?
Schedules syncs will never be really possible as apps on iOS can be terminated by the system at any time and then have no option to re-open themselves except for using local notifications. We might have something like this when the new sync technology has made its way to DEVONthink To Go.