Work Order sequence control

Is it possible to control the work order number generation until customer saves all details of the work order. Currently, in the standard scenario, the WO Number is generated at the time a user opens a WO Page/Form. In this case, even if the user does not enter any details and closes the WO Form, the sequence number gets used. They do not want to lose the work order numbers, so they wish to delay the sequence generation until work order is saved.

Is there any way that the WO Number is generated at the time of saving the WO.