Modifying the maintenance plan schedule

The backup should occur at a time that does not conflict with peak usage of the system. Use the following procedure to modify the schedule:

Open and log in to Microsoft SQL Server Management Studio.
In the tree-view, open the Management | Maintenance Plans nodes.
Right-click the plan, and click Modify. A Plan Design panel opens.
In the Plan Design panel list, select the subplan.
With the subplan selected, click the Subplan Schedule button in the toolbar. The Job Schedule Properties dialog box opens
In the Job Schedule Properties dialog box, enter the new schedule details.
Click OK on the Job Schedule Properties dialog box.
Close Server Management Studio and answer Yes when prompted to save changes.