Basically, GB test has no ramp up time and thus
starts from the set test time by user directly.
However, due to some cases where a buffer
time before test time is in fact required for GB
test, e.g., in conveyor where DUTs are tested for
GB by batches and certain buffer duration
needed for test leads or jigs connecting with
DUTs, the GB CONTACT setting practically
allows user to apply to customized scenarios
when necessary occurs.