This is the initial start time for the entry's set of test
cycles. This value is expressed in seconds since the Epoch
(Jan 1, 1970).
The scheduled entry MUST be cancelled prior to modifying the
start time. An 'inconsistentValue' return code is returned for
a set operation with a value other than zero if the
etsysIpSlaScheduleTestState is NOT 'inactive'.
Setting this value to zero cancels the scheduled tests and
the etsysIpSlaScheduleTestState transitions to 'inactive'.