Common sense (which is no longer common) and good engineering practice says to treat any engine the same, especially a very cold one. Give it a few seconds/minutes depending on the ambient temperature to find itself, let the fuel mixture/cooling stabilize, and then, load it up. Just the reverse for shutting it down. If the genny stumbles and stalls on start up, that should tell you something. (hint: I'm not ready to run yet!) If the genny runs on, backfires, or pings on shutdown, that should tell you something too! (hint: I'm still too hot and need some unloading time to cool off before shutting down)
When is the last time you saw a pilot jump into an aircraft, start it and catapult into the sky? Even on WWII aircraft carriers they ALWAYS give the engines time to warm up. Remember the space shuttle Challenger? What destroyed that and killed all the crew? (hint: temperature differential in the solid rocket booster shells)
Everything works fine, until it doesn't!
Chum lee