I still wouldn't worry, because this is really one of two things. If you start your engine from cold without your foot down on the accelerator and the smoke is black, it shows that your engine is in pretty good condition and it is successfully burning all of the extra fuel that has been injected into the cylinders, hence the extra injection is working well, no fuel is being lost un burned down the exhaust and the engine will have powered straight up. Does it start straight up or does it struggle a bit?
If you start your engine with your foot on the peddle, you'll notice a similar thing because you are in effect knocking out the cold start and filling the engine with fuel your self. You could have a go at reducing the amount of fuel that the pump is injecting into your engine, although I'm not sure where the adjuster bolt is on the Bosch fuel pumps.
I would't worry! It's just when it starts throwing out black or white smoke when the engine's warm that you need to think things over a little.
-Pos