The Free On-line Dictionary of Computing (19 January 2023):

since time T equals minus infinity

   A long time ago; for as long as anyone can remember; at the
   time that some particular frob was first designed.  Usually
   the word "time" is omitted.  See also time T; contrast
   epoch.

   [Jargon File]


The Jargon File (version 4.4.7, 29 Dec 2003):

since time T equals minus infinity
 adv.

    A long time ago; for as long as anyone can remember; at the time that some
    particular frob was first designed. Usually the word ‘time’ is omitted. See
    also time T; contrast epoch.