The scheduler will run by default run every 30 minutes. In some cases you might want to run a sync cycle in between the scheduled cycles or you need to run a different type.

Delta Sync Cycle
It could be that you have an urgent change which must be synchronized immediately which is why you need to manually run a cycle. If you need to manually run a cycle, then from PowerShell run:

Start-ADSyncSyncCycle -PolicyType Delta

Full Sync Cycle
If you have made one of the following configuration changes, you need to run a full sync cycle (a.k.a. Initial):

• Added more objects or attributes to be imported from a source directory
• Made changes to the Synchronization rules
• Changed filtering so a different number of objects should be included (e.g. Adding a new OU to the filter)

If you have made one of these changes, then you need to run a full sync cycle so the sync engine has the opportunity to reconsolidate the connector spaces. To initiate a full sync cycle, run:

Start-ADSyncSyncCycle -PolicyType Initial