This is one of the more important questions to be addressed when smoking.
When you initially fire up a smoker, you will be generating undesirable smoke.
This is normal.
The smoke will appear to be grayish white or white.
This is because the wood or charcoal is in what we call the primary burn.
The wood is heating up and is below 575 degrees.
It is not burning yet.
When the wood temperature moves above 575 to 600 degrees, it is in the secondary burn in which the wood will start to release gases and this is what gives off the flames and provides a good smoke for your cook.
Usually when this happens you will see a bluish white smoke coming out the chimney which is perfect for smoking.