Abstract: The advanced detector era will see unprecedented sensitivity to gravitational waves over a broad frequency range. The first direct observation of gravitational waves is expected to occur within the next few years, yielding new information about the physics involved in energetic astrophysical events such as binary neutron star mergers, or perhaps even galactic supernovae. With the installation and commissioning of Advanced LIGO (aLIGO) instrumental upgrades nearing completion, the first aLIGO observing run (O1) is slated to start very soon: summer 2015. I will cover the interferometers' commissioning timeline and the lead up to O1 with a focus on preparing to analyze transient gravitational wave signals. I will give an overview the goals of detector characterization and examples of some of the most pressing issues in recent data that may hinder confident detection and accurate parameter estimation of transient gravitational wave signals.