Smoke at startup for a diesel is normal, even blue smoke on pre-tier 3 and tier 4 emissions.
Reason is diesels are awfully inefficient on cold startups until they get up to operating temperature.
Blue smoke means you are burning oil so monitor that. My 2007 Duramaxs have a little blue smoke at start up. One is at 46k miles and the other 110k, but I have deleted the grid heaters and EGR's on both.
Black smoke is partially burned diesel.
White smoke is unburned diesel, usually an injector issue.