Use the "Start again only on" check box to synchronize only on certain days of the week.
A timed synchronization will occur on each day of the week which has a check mark next to it.
The "Don't Start" button lets you create a time window during which peridic syncs won't run. If a timed sync is scheduled to run during this time, it will not run, and if it's a periodic sync, it will run at its next scheduled time, after the expiration of the time window.
