The following stackoverflow question asks for how to get the creation date of a job within Jenkins.
http://stackoverflow.com/questions/25724894/how-to-get-the-jenkins-created-data-and-time

I haven't been able to figure out a way to capture the creation date of a Job from jenkins core. I did find that using the jobConfigHistory plugin provides detail on the create operation of a Job which would be possible to scrape, but I would prefer the core expose this information. For some reason, jobConfigHistory usually shows two change operations before the create operation...which is also a little strange.

Please let me know if I've overlooked an easy way to get the date of creation of a Job. Otherwise, maybe someone knows how to extend jenkins to provide this detail in the project_config of the jenkins api? Or even a way to easily get the create date from the jobConfighistory plugin using groovy script? I'm still researching myself.

Thanks.
--dave
http://dave.thehorners.com/tech-talk/programming/226-testing-release-engineering-ci-building-code-that-deploys-and-runs-like-it-should