Between the Initial Flash and the Shock Wave

If you live far enough from Ground Zero like I do, there is one important step to take after a light brighter then the Sun gets your attention.  If you are 20 miles back, the shock wave will take at least two minutes to get here.  Even a one megaton blast will produce only light structural damage this far out.  But that includes broken window glass. This is both a personal hazard from flying glass shards but also a dangerous mess to clean up.  

If you have glass doors, open them so the shock wave will go past not through the glass.  Open all windows.  The outer facing panes may well break but likely be held from farther entry by the inner window.  Remember that most windows now are double pane.  I suspect that most combinations of four panes will prevent shards inside.

Of course, the outfacing windows may well be broken but close the windows and tape plastic over the broken windows to keep fallout from entering.

I am not sure what I am missing.  Hints?