Advanced option. Should probably be left unchecked.

The build quiet period is designed to assist with CVS checkouts by waiting for a specific period of time without commits. Normally you want the checkout to reflect the time when the quiet period was exited successfully. Select this option if you need to re-enable the legacy behaviour of Jenkins, i.e. using the time that the build started checking out as the timestamp for the checkout operation. Note: enabling this option can result in the quiet period being defeated especially in those cases where the build is not able to start immediately after exiting the quiet period.