Adding BUILD_TIMESTAMP to Jenkins env vars,

DST is not enabled by default. If your location uses DST, you can enable it by setting the timezone to the correct city such as America/New_York. Set the timezone to corresponding city, such as America/New_York to display Daylight Saving Time format when Daylight Saving Time is enabled.

Add more var names and formats if you need.

For additional variables you can define shift (days, hours, minutes) which will be added to build timestamp. This allows to run build plan with previous day specified as parameter.

Export build timestamps to build env variables.

BUILD_TIMESTAMP exported by default, and you can add more variables with different format patterns in Global Configure page.

They are available in Maven build and Gradle build as built-in properties/variables as well.

Maven:
As defined property in pom, equals to

System.getProperty('BUILD_TIMESTAMP')

Gradle:

System.getenv('BUILD_TIMESTAMP')

Shell:

"$BUILD_TIMESTAMP"