The Snapcenter 4.2 Cmdlet Reference Guide has you covered! From page 211:
Use this parameter if the source SCV host and the
destination NDB host are in different time zones. Value
should be a positive or negative time offset to adjust
scheduled backup run times. Specify time difference in
the format hh:mm:ss, such as 06:00:00, or -06:00:00 for
a negative value.
It is not a required parameter, so if that doesn't apply to your situation, then it can be ommited from the command.
EDIT: if you run "Get-Help Invoke-SCVOVAMigration -full", it will show you all of the parameters and their descriptions (and whether they are required or have default values, etc.)