Working in Northern Virginia, we have had a couple of building evacs in the past year.  These are normally fire alarm related.  The way I go about keeping my kit with me is to keep it in my laptop case (actually a really large backpack for a serving tray sized laptop).  Anytime I leave the building I grab my bag like I do every day when I go home.  It is the most natural thing to do versus training yourself to grab a BOB that is not your everyday commuter bag.
Bill