Manual control of glowplugs, after engine fires

[zyewdall]

Question on manual control of glowplugs.

The engine starts great normally with the automatic glow plug controller, but this morning (mid 20's F) I started it three times before it would run.  Fired up immediately each time, but then died within 10 seconds.  I was wondering if the glow plugs should be kept on first the few seconds of the engine running until it builds up some heat. Or will this destroy the glow plugs or worse.  I was thinking of wiring a N.O. poshbutton switch on the dash in parallel with the glowplug controller so I can do this.  I guess I should hook up a test light to the glow plugs to see if the automatic controller is already doing this.  I know it turns them off when they get up to temp because I can hear the relay click back off and see the voltage rise just before I turn the key to start, but I don't know what they do after it starts.

This is actually an '84 Mitsubish 2.3L, but I figured the glowplug question should be same as for VW's

Edit: I'm pretty sure they're quick glow plugs.  They only stay on about 10 to 15 seconds even on days like this morning.