Early time dynamics and constraints on medium evolution

In relativistic heavy-ion collisions, a quark-gluon plasma (QGP) is created whose pre-equilibrium evolution includes a rich variety of exciting phenomena of Quantum Chromodynamics. In these Proceedings, we provide a short overview of our current understanding of the pre-equilibrium dynamics of the QGP from a weak-coupling perspective and highlight recent developments. Focusing on new studies, we then discuss how initial stages of the QGP medium may impact hard probes including direct photons, dileptons, jets, and heavy quarks. This introduces promising opportunities to obtain experimental signatures of the pre-equilibrium QGP.