It’s about time. We are now on Instagram!
1660s, from French préliminaire and directly from Medieval Latin praeliminaris, from Latin prae- "before" (see pre-) + limen (genitive liminis) "threshold" (see limit (n.)). A word that arose in reference to negotiations to end the Thirty Years' War. Earliest attested form in English is preliminaries (n.), 1650s.