bugzillapreview doesn't show anywhere the date of creation of Bugzilla reports, see for instance https://bugzillapreview.wmflabs.org/T6868 (Reported: 2014-03-22 18:12 UTC)
In an ideal world, right below the description a first status would say
Qgil created this task. Via Conduit · Mar 22 2014, 18:12
In our team meetings @chasemp has explained how difficult is to show this because of... Bugzilla or Phabricator API not supporting this (or something along these lines, please add the proper explanation). If we can do this, great. If we can't do this, then let's use this task to document why.