ok, I know its normal for diesels to smoke in frigit temps until they warm up a bit, but is this bad for them? Sometimes I forget to plug it in.

 

It's not bad for them. It's just fuel-rich exhaust you're seeing. I wouldn't start it then let it idle very long though as you risk contaminating the crankcase with fuel. Start it, "wake it up", drive off easy for a couple of miles is my modus operandi.

 

If you are going to let it idle for any more that a couple of min., do the engine a favor and crank up the rpm to about 1100 or so. It will warm the cylinders slighly more a little quicker.
Tom

 

It would help to up your timing to 15.5 degrees.If you have a exhaust brake you could turn it on.