Order the block heater cord if you don't already have it. Geno's Garage will be about the best cost.
I've started my '05 numerous times at -20*F when I was working out of Leadville; it would miss on a couple cylinders for a few seconds. I wish I could have plugged it in where I was staying.
At home, I plug mine in for about 3hrs before start when it gets in the 30's.
Using the block heater is easier on everything. Quicker warm up is just one of the benefits. Thinner oil from being somewhat warm, faster/easier cranking and less grid heater time (glow plugs for the other guys) puts less strain on the batteries.